You know, you don't have to do anything you don't want, or justify yourself....
But I promise people who do rescue (any species) do so to help the animal, not because they believe it's lucrative. I don't rescue reptiles right now - I don't have the know how. I have rescues dogs. Three of my five are rescues. Two of those three have cost me thousands- literally. Do I care? No. I didn't do it to make a sound fiscal decision, I did it because I wanted to help those animals live good lives, and I had the money available. I donate to charities, too. It's something I do that makes me feel good.
If it doesn't have that payoff to you, no harm no foul and no ones business. There is no one size fits all here, and no need for judgement either way.