He wants to chip in perhaps and wanna spend fewer skills.The lowest skill count way to reach 100 would be through mindforce I believe. This is based on the limited number of ancillary skills you get compared to more traditional hunting ways. If you only stuck to one profession the whole way. And didn’t do any other activity you could probably hit 100 without 250 HP even. The only other professions you would get skills in are defensive and looter maybe paramedic.
That being said, I don’t think anyone’s goal should be to have the lowest skill count and only focus on a professional level of 100. Nothing special happens at 100 other than you get a new title.