Yes, but not focusing on money is how you end up building a business that sells dollar bills for $0.90. A few "for fun" startups have blown up in the past (Instagram, Snapchat, YouTube), but the reason majority fail is lack of business plan for how to actually monetize what they are working on. I don't consider focus on sustainability for a business to be a bad thing, though if a VC handed me $10m to spend trying to buy users I won't say no.