> I bust my guts trying to make things a little better

Don't.

> I earn very little and get back nothing.

Exactly. You need to be more mercenary.

> Why bother even trying?

For things you care about. Your family, your self, maaaybe some close friends. If you're going to invest in a project, make sure you own it or have significant equity.

The world is chock full of vampires looking to exploit helpers. Don't let them get you.