If by definition of "success" you mean getting rich and improving the lives of people in the process, then does it really matter if other developers will start copying from them?

"If that happens to me, I'll lose all motivation to innovate any further"

Well, tough luck kid, but a free market has no morals. In a free market the law of the fittest applies. And you should be glad there are still free markets out there, in which people like us can thrive.