I don't understand this at all. In what world is there an infinite amount of hours I can work? Most people work 40 hours a week and if they work more don't get paid extra (barring overtime but do you work somewhere where you can just work 100 hours a week and put in 60 hours of overtime because you felt like it?).
Between weekends and just general downtime in week (I spend time watching netflix and browsing the internet and I read books in my commute) I have at least 30 hours free a week. If you're into stocks as much as I'm into wasting time entertaining myself then why not.
Assume
1. it takes an extra 500 hours a year to research and buy good investments.
2. you make $60 an hour
3. all your hard work delivers a respectable alpha of 3%(3% better returns than than the market)
You need to be investing approximately 1 million dollars to break even.