This is a sampling of currently available services and who they use for DDoS protection:
stresslab.app - Cloudflare
maxstresser.com - Cloudflare
sunnystress.com - Cloudflare
tresser.io - Cloudflare
ip-stresser.net - Cloudflare
hardstresser.com - DDoSGuard
zdstresser.net - Cloudflare
starkstresser.net - Cloudflare
stresserhub.org - Cloudflare
nightmarestresser.net - DDoSGuard
Just for fun head over to Cloudflare's abuse reporting site and try to figure out how to get one of these taken down. https://abuse.cloudflare.com/Now they hide behind Cloudflare who will refuse to turn over any information so that security folks can get them taken down. Unfortunately Cloudflare has grown too large that we can't just block all of it or depeer them like we would any other network that provided services to bad actors.
Most of the listed domain names are under US jurisdiction. That means the authorities should be able to take them down. If Cloudflare is found to have been knowingly enabling crime, it could face fines, and the CEO and other key people could end up in prison. The Cloudflare services have probably been paid using means that are under US jurisdiction. Those payment accounts can be closed and the people behind them tracked down and potentially charged with crimes.
Or at least that's how things work in the real world. The internet is still apparently too new for the authorities to understand how to deal with it.
Zero ingress puts the upfront bandwidth cost onto the attacker. Because... you actually may succeed to defend and stay up. Their success is not guaranteed, they might be shouting into the void.
Attack success (as in, "impact on you") is guaranteed if your ingress is chargeable.