People are individuals, all going through their own journeys. You might grow and change for the better if you're able to figure out how to be the best you, or you might change for the worse if made bitter by a life where it feels like no one is on your side and you have to take your due since it will never be given.
The important thing is: (1) People are twats for a reason, and (2) You can't fix those reasons for other people and make them less twatty, so the only thing you can control is how you handle less than ideal interactions. (Tip: most well-adjusted people don't jump to "lose hope in humanity"; the fact that you have means there's work you can do here.)