But, how feasible is it to start companies this way? Sure it may have worked well for them and it may even work incredibly well for your business. As hackers though, we know that just because something worked once, twice or 500 times doesn't mean it's the truth or will always work.
It's best to be prudent wherever possible and do some research into your market and pricing strategies. I'm not saying go off and create 5 year business plans, I'm just saying it definitely deserves some of your time cycles.