Once an IP in a botnet attacks someone, it ends up on a blocklist and can’t attack anyone else who uses that blocklist. This is a big part of Cloudflare’s DDoS model: if you attack one CF property (with non-volumetric DDoS) you will not be able to attack any others with the same bot for an extended period. This makes attacks to CF properties limited in scope and way more costly, because you have to essentially “burn” IP addresses after sending relatively little traffic.