Passion projects are what really matters. I think making everything about revenue is what's wrong with the whole world, and I think feeling the way you feel (you wasted your time) is a direct symptom of living under such a parasitic economic system. Our right to access the basic necessities of life is dependent on our willingness to turn a profit for some already-rich person. You didn't waste your youth, you used it well. It would have been a waste to spend such a wonderful time working yourself to death.