The most vulnerable are the ones who don't have friends or a support system nearby. Their only options are to put up with being constantly harassed, or cut themselves off from their community entirely.
So internet is not lead plumbing. It's more like early electric grid, where lightning could burn a house nearby. It's not going away, it will just get better.
That being said internet harassment is a genuine problem. And I don't have solution for it.
Twitter users are about 10% of internet users. And the problem looks lot worse than it is. Popular users are lot more likely to be harassed, and we are more likely to hear stuff from popular users. Most are probably like me, followed by my mom and one real life friend.
You're more likely to hear about harassment from popular users, but that doesn't mean lots of regular people aren't harassed too.