Everything is hard but very few people have still enough hands to even be considered neurosurgeons or an interest in using meth in order to perform the insane surgeries (need to stay awake and concentrate). Further few are capable of dehumanising people enough in order to be able to cut into them.
Plenty of people are interested in enough things to cover them but neurosurgery at least is almost life destroying in what it demands. I’ve never met anyone entirely whole that’s a neurosurgeon, so it’s kinda weird to imagine people would want to flock to it and we wouldn’t have enough people happy to do other work.