Do you realise that although you "lost 2-4 years of your career" you created a few dozen higher quality lives?

I think you have achieved a major life goal already that most in Silicon Valley do not. I don't know if HN is the place to praise such deeds, but you did your small part in hacking the world to make it better. Kudos to you, don't ever let it feel as a wasted effort. That's so wrong a way to think.

There are people who want to help others and their repeated attempts fail. You just went and did something that's working for 7 years.

That's a pretty successful startup in my book. It can't go viral for obvious reasons, but it's mature and stable. And you did it without HN :-)