But they have. It’s just they are so hateful and annoying that sooner than later they get banned or defederated. So they drop out of the face of the activity pub. Since no single entity can use an algo to force their views onto all users (ads or suggestion algos) they never resurface.
And of course crypto bros hate the fediverse, it doesn’t let them force their ponzi schemes with ads or SEOed posts. And most people here were initially pretty tech savvy individuals, almost all actively hostile against nfts and altcoins. As for Foss, they only like that the software is free, the freedom ideology is just lip service for them, they don’t actually believe. Case in point, Oracle. Foss? Free for me but not for thee.