The only situation in which self-hosting or ditching BitBucket/similarly large providers will help protect you from the fallout of historically-large, catastrophic attacks is if you do all of your development on the same local network as your hosted server (and don't rely on any internet services to access it).

And even if you diligently self-host every part of your own services (not as easy as just plop a gitlab/gitea install on a host you own and start it up), you have to deal with the fallout from internet-breaking DDoS attacks and other malicious activity if you want to use the internet to run or use your code: from congestion caused by compromised devices in your network "neighborhood" (same/similar ISPs or last-mile providers) to DNS outages to BGP hacks, we have seen time and time again that, if not exactly centralized, the systems that comprise the usable internet are certainly highly interdependent. Large-scale attacks of many kinds compromise them.

Instead of tantrums, it might behoove users to understand what kind of SLAs they can promise in order to operate their self-hosted services in such an interdependent environment. Some examples:

Do you need local power? A local ISP to be up? More than one? If you have more than one internet link, how do you pair the connections--if it's via BGP, what happens if the central authority on that has issues? If local power is down, does your local ISP's connection stay up? How long does it stay up (is there a node/amp somewhere on the line that cut to battery)? Do you need to access internet services by hostname? If so, do you do local DNS caching? If so, how stale can it get in the event of a loss of external DNS? Most importantly: how much (it's a nonzero number unless you're developing for yourself, by yourself, on your LAN) dependence on external services are you comfortable with, and how much time are you willing to spend eliminating the long tail of such dependencies?