There’s quite a spectrum between a 10-20min almost daily habit and trying to actually reach “enlightenment”. These 10 day silent retreats are a lot closer to the Bodhidharma sitting in a cave end of the spectrum. Probably not the first people to go a little crazy attempting that in Buddhist history. Given the context I would imagine it’s mostly overachievers but that is not really a healthy approach to religion or mental health (going hard as a mf)