[overfeed]

You are right, they don't have to do it themselves, but guess who's protecting the booters from other booters?

[l23k4]

Primarily specialist bulletproof ddos protection services like ddos-guard.ru, not "Cloudflare" as is the popular meme among clueless commenters.

[linkregister]

Most modern booters are not maintaining public websites that could be the object of DDoS attacks. They're renting residential IP addresses from free VPN users.