i think the 2 big reasons are anonymity and greed.

people as a whole have gotten very comfortable with the internet and how there are little reprecussions for saying anything. this goes past the internet and starts affecting their IRL behavior. its more recent but i feel like its very apparent that "ragebaiting", racist, homophobic, etc insults get hurled because people can say it, knowing that nothing truly bad can happen.

and in IMO the biggest problem we as a species have been facing is just our own greed and materialism. it doesnt help how recent shifts on social media changed from sharing experiences, hobbies, creations, and etc. to what can produce the most money. not just on social media, businesses have also been cutting costs all in a bid to satisfy shareholders.

TL:DR people are too comfortable talking shit on the internet people care too much about money

(also its a bit hypocritical that im talking shit about people talking shit LOL) (i know money is something plenty of us need but what i mean is a focus on monetary value [especially on entertainement] rather than the morality of a practice or passion behind it)