Why do people indoors at public places always listen to their phone at full volume?

Figure out their name. Figure out the conversation. Join in. Example:

Ashleigh! Don't tell your husband about our passionate romantic relationship!

Ashley: I don't know you!

Example Me: Ashleigh! You said you were leaving him, it's him or me!

Ashley: Go away this is none of your business!

Example Me: Ashleigh, Don't act like you don't know me. I've seen 100% of you not that long ago!

Be the chance you want in this world.

There is a special place in hell for those that do this or those that would do this. Risking a relationship…
Side note: I’ll see you there, I’ll bring the beer.
It doesn’t have to be that confrontational; if the same person is a repeat offender, listen to what they’re saying over a few weeks, and then start interrupting them to correct them based on previous things they’ve said.
Good way to highlight to them that they’re NOT in a private space.
Even better if you can get a group of people to join you in this.
Jesus christ 😂 thank you for this

The people I've seen do this seem to be trying to establish dominance and are hoping someone confronts them so they can fight. A pissing contest.

That, or, they are so self-absorbed that they lack the ability to realize that their behavior impacts others.

It's mostly because "fuck you, I do what I want."

I always assumed they're either trying to prove they have friends or they have no self-awareness whatsoever.

Because people are assholes. I say that in public I'm surrounded by assholes at all times. Then they want to act like I'M the common theme here.

No. I don't listen to my phone without headphones in public. Assholes do.

I don't IMMEDIATELY stop at the end of an escalator and just stand there. Assholes do.

I don't try to immediately get on the train as the doors open before people can get off. Assholes do.

I'm not a smoker at all, but if I were I wouldn't just start smoking in public places where crowds need to form, like bus stops, or lines, or even worse, indoors. Assholes do this.

I don't masturbate on the bus next to kids. Assholes do.

I don't pee in the stands of a crowd at a sporting event. Assholes do.

I don't go into public places and start shooting people with guns. Assholes do.

I don't take an entire family to the mall so we can all walk around the food court, grab all the free samples, but instead of them eating it, I get like 30 free samples, and thus a free meal. Assholes do.

You've seen some shit huh?
- The fact that I haven't been arrested for setting people on fire is only a testament to my will power to be the peaceful person.......because I REALLY want to just set these people on fire.
  Is that wrong? Would I be in the wrong for just setting these people on fire?

Entitlement

This makes me so irrationally angry. Where I live it's usually just 12 year old kids on the bus who forgot headphones but still want to listen to the narration of the world's shittiest tiktok videos rather than reading the captions. It's fine. I'm fine. Everything is fine.

I don't think you're being irrational 😂

Shit tier humans. Same sorts of people who don't put carts back at the store.

Some fucking clown did this at the gym the other day. She was on the elliptical and was blasting music at full volume from her phone instead of using headphones. It absolutely shocked me how fucking oblivious and inconsiderate people can be. I also saw a toothbruth left in the sink and flip flops left in the sink at this gym too. Fucking clowns.

It’s selection bias. Almost nobody does it, but for those odd people who do, everyone gets to hear them.

Just like the people who speed, weave and pass everyone in traffic; there’s relatively few of them, but they affect everyone, so it feels like more people are doing it than actually are.

All it takes is for one person who normally uses headphones to have their batteries die, forget the headphones, or something else totally explainable, and suddenly they can be affecting hundreds or even thousands of people.

Of course, there are also other people who just regularly talk loudly on their phones and have the speaker cranked to max; I suspect these are people with ear/hearing issues that find headphones uncomfortable and don’t realize how noisy they’re being because they can’t hear it themselves when others do it (because of hearing issues or because they never shut up).

Note that you never notice the things you are doing wrong. So you yell at the person tailgating you, while not caring that you are following too close. When someone else doesn't use a turn signal they are an idiot, when you don't it was a honest mistake.

They want you to hear their superior musical taste \s

They are subtly asking for blunt force trauma

I have one that bothers me more. There are people who park their cars in front of random houses at night, I assume it’s delivery people or ubers taking a break. They will have their phones connected to their cars; speakers at max. I can hear their whole conversations while I am trying to fall asleep. Happens about once a month where I live.

That I might have some insight into. In our car the speakers are quite wierd in that you can have the volume not even halfway and just so you can hear the person talk clearly, but outside the car you hear it so much better and louder. If you have never been outside your car when someone is taking on the phone you will never know about it, because from the inside you wouldn't suspect it being so audible outside.
- I didn’t know that, could be the case. I just assumed it was the same people that drive around with their windows down blasting music. It’s likely the same crowd that is being described by OP.

I wish I had the balls to start up my own fake conversation next to them. Talk about how your proctologist/obgyn visit went in excruciating detail.

Not "always". In fact almost never where I live. And if they do, it is very likely we witness some glorious russian culture on display.

Weird isn't it? We only tend to notice those who are noticeable

No they don't, you only notice the ones that do. It's called toupee fallacy.

Some people are hard of hearing. It annoys me but I know people who turn on speakerphone immediately since they say they can't otherwise hear.

Surely headphones/earphones would be even better.
Oh, I took it to mean walking around listening to music at full volume. That's way more common around me than speakerphone. You'll be in a store, and hear 10 different people playing 10 different songs.

Why do people post hyperbolic questions they know the answer to lol

My opinion might be misled, so I'm asking for others' opinions to get a different perspective.

I've never experienced this. Everybody here uses headphones of some sort, and I have no idea how loud they're listening.

They don't care about anyone else. They believe that they shouldn't care because other people do that crap, and/or if someone is annoying they should block it out with headphones. Asking them to keep to themselves is worse than just blocking it out in their eyes. I cut ties with people like that. "My" mother is like that, blasting stupid duolingo games in public areas. Bitch did that for a whole train ride and also in the elevator, and found it Funny™ that I asked her not to do that.

Short answer: they don't care and are most likely marijuana addicts who beat their significant other when they withdraw and/or are emotionally abusive. Incredibly red flag.