who can be mad at that

Once I was on my bike and someone stopped to let me across the street, holding up a ton of traffic. In order to not be rude and force everyone to stop for me I rode across as fast as I could and then got hit by a car coming the other way.
Don't be polite. Be predictable.
- For sure, I think drivers often make calculations like they're being nice, but the risk to a walker is way higher than a driver and so they shouldn't be surprised when the walker doesn't take the wave. I slow down and meander as a pedestrian when there's a busy 4 way and then jog across, if people stop early "just in case" I feel put at risk for niceties.
  
  Agreed. You're not taking the risk, don't make the decision for me. I'll go when I feel it's safe for me to do so.
- I bitch about this constantly. My partner and I love to walk around town, and people will stop let us cross at weird points in the street. My partner is always happy about this and I correct them every time that "I'd prefer if they were predictable. What if someone behind them got annoyed and didn't see us and decided to go around and hit us?"
- I saw something similar on my way to work. Some pedestrian was trying to jaywalk across a busy, high speed road. A car stopped in the middle of the road to "be polite" and help them cross. What the car and pedestrian couldn't see was that an additional car in the next lane was going very fast and did not have visibility of the pedestrian. Their view of the pedestrian was blocked by the stopped car. And the pedestrian's view of the fast moving car was also blocked by their position at the stopped car.
  The pedestrian crossed the whole way of the road, but came maybe a foot away from being hit by the fast car. I was afraid I was about to watch someone die.
  Don't stop for people at odd places in the road unless it's an emergency. Sometimes "being polite" for someone is actually dangerous.
  Edit: I will say that there is still partial fault with ALL parties involved. If you are driving the speed limit and see a car suddenly stopped ahead in the road, slow down. You don't know why they are stopped and there might be something in the road. But both the pedestrian and the stopped car should have done things differently.
  
  I think there's also an education problem. During my driver's ed class, I was told that pedestrians always had right of way and we needed to yield to them, which is simply untrue.
- Did I misread you or are you implying that it was the car that let you cross the one at fault?
  
  The fault is obviously the driver who hit them, but also the social pressure of holding everyone up and making a quick decision to go and clear up the intersection.
  This isn't unlike a situation where a truck stopped to help my sister turn left out of a business he wanted to turn into on a 2 lane 2 way. She had no visibility, and the dude was angerly waving her to leave for his wide turn. She let the social pressure get to her, went out to peak around him, saw the far lane was clear and went, then got tboned by someone zipping around him. She never would have tried that had he not made her seem like she was the unreasonable one making him circle the block again or make the wide turn into the other lane to get in straighter... Course he didn't stop to be a witness either.

"Thanks for not causing me bodily harm with your machine"
- Had a guy pulling out of a parking lot while I was walking on the sidewalk, with him waiting on the sidewalk to pull into traffic. He actually bothered to back up a bit so I didn't have to walk in front or behind him. It wasn't necessary but a cool gesture. We could all do a little more of that in the world.
  
  I had the same experience earlier this week, except they didn't back up and instead started driving, forcing me to jump back to avoid being run over

Note that this principle does not extend to other drivers. Do not be nice while driving. Behave predictably, and follow the rules of the road.
Being nice can confuse drivers and cause accidents.
- On the other hand, if you are driving and see another driver stop assume there's a good reason for it and should at least slow down enough to stop at a moment's notice.
  Your advice is a good argument to forbid people from driving.
  
  You should always be prepared to stop.
  With that said, yes. It’s a dangerous activity that is unfortunately required where I live.

I hate that. Just let me cross without waving your finger at me to cross. I don't burn fuel, I don't hold up traffic, you the driver do.
- Same once I passed my driver licence and learned pedestrian had total priority on crossroad strip I realized you don't have to thanks people for following the rule the same way driver don't thanks me when I wait a the red pedestrian light
  
  I like to thank them for not splattering me ig. It's more of a fear response than anything.

I like to give a thumbs up to drivers who stop for me. Not because they're doing some huge favor, I just like to be encouraging.

I pretend not to see nor hear them until they speed off in a rage because I gotta be the change I want to see.

A small mote of light in a dark world.

Driving a car is a sin, and the gods will punish all of us for your hubris. They'll send droughts, famines, floods, fires, and hurricanes to smite us all because you drove a car.