Have you seen men around you completely changing career in their 30s? How did it go?

Did it at 40. Left a dead end career in IT after yet another layoff, and became a mailman. It's really not so bad. I make just as much as I did in IT, which is a real indictment of IT, and most days I'm done by 2pm. There are some times around Christmas where I might cover extra routes for the money, in which case I'm working until 8pm. But that is completely my choice, and I get paid very well for doing it. One pay period during Christmas, I got the extra route pay plus a boot allowance which doubled my pay for those 2 weeks. That would never happen in IT. The best I could hope for after getting the 2am emergency call was that I got to work from home the next day (pre-pandemic). That's it. No extra pay, no extra time off, because my "on-call" pay apparently covered that. And I didn't make any more than my base pay as a mailman. This was really the best decision I've ever made.
- I make complex CAD designs all day and I dream of leaving it to become a garbage collector. The fixed schedule is very appealing.
- I make just as much as I did in IT, which is a real indictment of IT,
  That's surprising indeed! May I ask you where you are located? (you can just give continent if you don't to give countries)
  
  I'm in Canada, in an area heavy with tech companies. But I was also stuck in Support. I took a Support job since a friend was working there and they offered me almost double what I was making as a QA developer, which that point was completely lost on the people I had been working for. But that was the worst decision of my life. They promised me a chance to move to C# development if I started in Support, which is a big part of why I took the job. After 5 years of broken promises, they laid me off unceremoniously. After that, it was just a string of shitty support jobs at about the same wage each time. My salary had stagnated for a decade. New developers were starting at more than I was making after 10 years. So after spending more than a year looking for a job after the last layoff, I was desperate and starting applying to everything. This job came up, and after a few more months of apply to IT and coming very close to not one but two different developer roles that both evaporated after I was told I had the second interview with the director, I decided being a mailman wasn't so bad. I just stopped apply to IT and embraced it.

Yeah. Saw a man go from CEO of his own company to follow his dreams and become a pastry chef.
Soon after, he also became an inmate because he paid for all that with money that wasn't his.
So, you should probably avoid spending money that isn't yours.

I went from banking to project management to medical device manufacturing.

I did that myself, though partly it was just because I hadn’t really settled on a career to begin with. Early 30s and before was just alot of low-level BS fast food, call center, and some light manufacturing jobs, all second shift. I finished up college relatively late in the game (in my 30s) and fresh out of college got into graphic design and I guess since I’ve been doing it a decade now, it’s a “career”.
I was relatively directionless before and shirked responsibility. My only priorities were getting enough money for rent, beer, and food, with no real idea of what I wanted in life. Then suddenly I fell into a role where I was given tons of responsibility and relatively little oversight, it made me have to get somewhat self-disciplined. Add in a kid and student loans and I really needed to get serious about things.
I’m definitely happy I got into, it was a change that has paid off in spades. It’s like an actual job job with colleagues and an industry I’m part of, not just random people coming in off the street every few weeks until they fail a drug test or quit in a rage, or low-level work where I’m treated like a tool. People actually appreciate my work and sometimes I’ll see my work in public, so that’s cool.

I went from Paramedic to sous chef in my late 20's. Then sous chef to banking to hockey arena manager in my 30's. I couldn't have stayed in one job. I would have gone crazy. Also live your life don't live your work.

Early 30's and already made 2 pivots since leaving my 20's. I will say this, employers aren't the brightest; you can tell them that you have a master's degree in that field and that you have no relevant experience yet lay you off later for not knowing how to do the job without being given training.
Whatever, ended up where I am way more happy and making more than the start of this whole career changing thing.

I recommend the book Range, by David Epstein. It makes the point that people can be more successful when they bring different skills and backgrounds to a task or job than if they only narrowly focus on one area their whole career. It’s got lots of examples, discusses what kind of environments reward narrow vs broad range, etc., and overall is a strong endorsement of career hopping.
Life is short. If you’re not happy with what you’re doing, you should make a change.

Yes, both change roles, industries, even fields. Some have reeducated, went into business for themselves.
It's seldom been easy for any of us, but the change is empowering, the suffering lessened, and the potential for betterment great.

A buddy of mine joined the navy in his 30s, and it allowed him to move into IT.
I've always had coworkers ditch IT and go into trades like electrician or welding. They seemed much happier.
- I left IT and started doing concrete work. Manual labor is much more rewarding. But, I'm leaving this soon as well, I work with a bunch of right wing racist shitbags and it sucks.

I went from plumbing and hvac sales to truck driving. It's great, I don't have to deal with customers, I make more money, and I just listen to audiobooks all day.

I completely changed my career around 30 years old because 2008 devastated my previous career. It was rough at first but turned out to be a real blessing. My new career is easier, pays way more money, and I actually love it.

Quit my admin job in November of 2022 to go back and refresh my software Dev knowledge at a bootcamp. It was great, loved every minute of it but I've been struggling to get a job since due to the historically bad year for layoffs in tech. I'm incredibly lucky to be in the position where my partners job can support us whilst I'm looking though so I can take my time and wait for the right role to come around which takes a lot of the stress of being unemployed off.

Currently doing that myself! I'm 33 and I've been a customer service rep and account executive for 10 years in manufacturing and supply chain. I found an entry level analyst position in insurance and it's going really well. Money is very tight, but I finally enjoy what I do and I like where my career is headed.
- Sounds great, good for you!