I can't agree with what you're saying. A business is successful if it generates profits at a lower cost, period.
I agree that on a personal level, it's not the same. You can consider yourself successful without necessarily generating profits, and I agree that you should pursue your happiness, which isn't the same as just making money.
But in my experience, if someone has to ask questions, it's because they're not clear about what they want. You talk about catharsis, but making a decision like the one he's proposing has consequences, consequences that I think he doesn't fully understand. He's chasing an idealized dream, and if that dream doesn't come true (which is most likely), it turns into a nightmare full of frustrations where he ends up questioning himself. At that point, there's no catharsis, no happiness, no success, but rather depression. And that risk is hidden from him behind pretty words like being persevering.
If he wants to take the risk, it's his life, let him do it, I wish him the best, but he should do it fully aware of the risks and the reality. If he's clear about what he wants and understands the risks, then, normally, those people don't question whether they're making a mistake, because they know what they want and what they're aiming for. That's the difference.