Gaming tends to attract a population that is tech-savvy (means), competitive (motive), and has copious leisure time (opportunity). Combine those three things and you have the kindling.
The spark, I think, is due to the fact that the crowd was historically quite young. That means three things. First, impulsive. Second, nothing/less to lose (someone with real assets they Worked Hard For wouldn't Risk It All over an in-game spat). Third, might not've learned how to handle competition in a healthy way.
A DDoS attack is a crime, but the sort that most law enforcement don't really care about at least in the context of a small-time game server. It's kind of the modern equivalent of knocking down mailboxes or shooting out traffic signs with a shotgun. Both things that cause actual damage that costs actual money, but which teenage males have been doing probably since the advent of mailboxes and shotguns.
Huh, I've only seen that with VPS hosters and thought it was related to game servers causing high CPU load on shared resources.
Like IRC back in the day :P
I have used Cloudflare Spectrum to prevent attacks. It does work incredibly well but the cost is significant.
As for 3rd party copmanies, I do hate to rely on cloudflare for this. It is the worst business relationship by far I have ever been in, but yet there are no good alternatives we found.