i think it's good idea to full time on bitcoin, it's not diffirent with your real job, you can be progamer or open new startup, then you can withdraw your bitcoin and use the fiat. it's a normal nothing diffirent with your job.
It's could be a great potential for programmers or those who has related educational backgrounds to do that, but its hard for people who haven't. It's fair to see people who don't want to go full time on bitcoin, because I'm sure most of them don't learn programming or crypto world.