

My favorite is Barry Marshall. He thought there was a connection between bacteria and ulcers, which was an unpopular opinion at the time. So he intentionally drank the offending bacteria, got sick as expected, and then people believed him.
More here, including (which I didn’t know until now) cardiac catheterization.
I’m sure better sources exist but https://www.discovermagazine.com/health/these-five-doctors-experimented-on-themselves-and-made-big-breakthroughs
Fail2ban config can get fairly involved in my experience. I’m probably not doing it the right way, as I wrote a bunch of web server ban rules — anyone trying to access wpadmin gets banned, for instance (I don’t use WordPress, and if I did, it wouldn’t be accessible from my public facing reverse proxy).
I just skimmed my nginx logs and looked for anything funky and put that in a ban rule, basically.