If youre talking about a vocational hobby.... like something on the side you do to make money in your spare time.... then i don't see any problem with this plan. But if youre looking to start a real business, llike something that makes enough money to support a person, i think youre severly underestimating how hard it is.
90% of new, small businesses fail. My bet would be that the number is closer to 99% if you only count people who tried to start a business while working a job elsewhere.
Yes, i know there are probably dozens of anecdotal stories about people who beat the odds. But thats kind of the point... they beat the odds. They had a bad plan and they got lucky, Mazeltov to them, but most of the time it isnt going to happen.
You don't build a successful enterprise working part time, it just doesnt work. And a guy working 40 hours a week at his job and 40 hours a week at his business is half assing both things. "Learn to think fast on little sleep" just doesnt cut it.