By the time you're building (or buying) the necessary highly esoteric and expensive ultracentrifuge setup I think you would be well outside the realm of "hobbyist" unless someone insists on the most unreasonably pedantic definition for the term.

Unless we're only considering final assembly. Just gotta get that weapons grade fissile material supplier lined up. That might or might not qualify as rich hobbyist territory depending on how high a price tag is permissible.

so which one is it here?

This subthread starts off with the argument that the big corps will never beat the little determined hackers, one of the founding myths of the early internet. And then every now and then a strong little branch of the argument runs up against an example and it becomes well sure, the little hobbyist hackers don't have anything there but that is because the big corps/gov/billionaires/whatever put so much into beating them.

I mean reading it all certainly sounds like the people on the little guy's side are overestimating the value of pluck, an observation Hollywood generally makes just before the heroes with pluck win for ever!