Crowdsec does not provide DDOS protection in the same manner as Cloudflare. You can use crowdsec to block the traffic at your server, but it has already reached your server, and will be using up your ingress bandwidth regardless. So if you were DDOS’d, your site will go down.

Cloudflare prevents the traffic ever reaching your server, while allowing the legitimate traffic through. They block it on their servers, which have much higher bandwidth than any VPS provider has.