So I would say that it's a little of both. Profit wouldn't hurt, but primarily it's about the idea. Even if I never made a dime from it and just broke even, it would be worth it to me. And I say change the world, and I guess I mean it, but a small subset of the world. Perhaps 10% of the population of developed countries could gain benefit from my service. It's probably not even that good of an idea, however I have gotten quite a bit of support from communities of people with mood disorders that I've posted about it on.
The idea by the way, I'll write a more detailed explanation about it when I'm on my computer, is basically a mood tracker that your therapist/psychiatrist, and potentially friends and family, has access to if you as the user grant them that access. They can view your check-ins and mood graphs at any time from a professional/support account. It also automatically notifies your supports, mainly your mental health professional(s), but also family and friends if you're linked to them through a support account, through text and email if you mark yourself as having suicidal feelings, or feelings of harming somebody else.
Having dealt with depression I know for a fact that actively seeking help was not a concern of mine at my lowest points. However, something as passive as marking my mood as suicidal on an app or website, that's something I could do. And it would in turn have the same effect as if I texted my therapist about my feelings. Along with those features there's a bit more to it that separates it from other mood trackers but I'll only explain those if you're interested in hearing more.
So it's probably not the world changing idea I made it out to be, but I think it could help in the treatment of those facing mood disorders, by allowing their psychiatrist or therapist as well as family and friends to play an active role in monitoring their mood and helping at the lows or highs (for those with bipolar). Maybe it'll never catch on, but even if it got a few hundred users whose well-being was benefited by it, then it's worth it. If it helped saved even ONE life, then it's worth it.