Why do you feel entitled to other folks money just because they have more than you?
Because this is a society. In society, there is a contract where people contribute to the general welfare of the whole society. As part of the middle class, I contribute what I can, and as part of the upper class, rich people should contribute what they can. Characterizing it as "feeling entitled to other folks' money just because they have more than you" is just plain wrong and silly, but you already know that.
Why do people think they should never have a set back or everyone should be middle class?
I haven't seen anyone say that. Sure, there will be set-backs. Losing everything because of extreme medical bills is not a set-back, though. A set-back is getting laid off and maybe having to take a worse job than you had before, for instance.
No one is saying everyone should be middle class, but the middle class is shrinking. The median household income is about $50,000. That means 50% of the households in America make less than that. You can get by on that with 2 people, and you could make it work for 3. But it's not middle class, and that means half of households are below middle class. Wanting people to not lose everything because of a medical emergency is not "thinking everyone should be middle class".
What are savings for after all? Medical bills can never touch your retirement or take your home away.
Savings are great, if you can afford them. When you're supporting 3 people on $50,000, you're not going to be able to have much in savings.
People can file bankruptcy and start fresh.
Sure, because it's that easy.