Exactly. I always find it amusing when people say they did something for 0$ by working in their spare time.
This calculation doesn't make any sense. Can you build the initial Google project in your spare-time? Probably, if you find enough qualified volunteers.
Does that mean it's a viable business?
Absolutely not.
You need to check how much you would have get paid when working in your last highest paying job... (Even when you do things in spare time)