No-one should be surprised in the slightest.
Every network that has done anything was bootstrapped with some initial cohort and that cohort heavily influenced the trajectory of the platform.
Gab and Parler went to shit because they became dumping points for alt-right nonsense. Tribel the same for extreme leftoidism and you can guarantee Blue Sky will end up in the same place.
#nostr being an open protocol where users are incentivised to contribute content that others will appreciate is the only one with a chance to break out of the mould. Having Bitcoiners as early adopters means itās more technical than other platforms but itās full of builders and people who want to see meaningful growth.