Short answer, it's because
a) we like other humans and want what's best for them
b) we lived our whole life under neo-liberalism/conservatism and all we see is constant decline in the quality of everything
c) we have been exposed to less pro-discriminatory propaganda than previous generations
d) we are better at navigating social media since we grew up with it, so we're better at filtering disinformation/misinformation than older generations
e) we don't watch the news, and without their influence we are more likely to have non-mainstream views based on your own values
f) with social media, we can see firsthand that a lot of people with authority lie, say dumb shit and are hypocritical. most times when a politician or person with authority does/says dumb shit, someone's filmed it and it goes on the Internet instead of getting cut in the news segment
g) ever since we started getting old enough to start caring about politics (for me it was at 12), Trump is the *main* guy. this is what politics are for us, we never experienced anything else and on top of that, he keeps winning
h) we don't trust authority, since in our view, most of the people who have authority (like trump) should never be near it
i) we were never under the illusion that there were safeguards in place in order to prevent corruption/crime in politics. our only experience is a comic book style villain who just does increasingly illegal/immoral/stupid shit because ultimately, the only "safeguard" in place to prevent it is pinky promising you won't do fascism
j) since we learned that rules are often made by unqualified people who don't have our best interests at heart, we are more likely to stand up for ourselves when we think something is unfair
k) instead of our mentality being "life isn't fair, get over it", it's "life isn't fair, we should do something about it"
l) we can't afford groceries or housing
that pretty much sums it up. i could've kept going but it's just a Twitter comment that will be read by like 5 people