Realistically, most people can't and/or shouldn't do this by building a business or working at a startup. Both of these are very risky and won't generally accomplish what I think the parent comment implies. Instead, the more reliable way is to invest as much of your income as you reasonably can in securities like stocks and bonds so that over time you are indeed making money doing nothing. Also, if your company offers stock options, opt for those if you think the company is going to do well in the future.