There are other sources of energy. With helium, once it's gone, there's nothing to replace it.
Jupiter's atmosphere is about 25% helium. And then there's the other gas giants, and the sun itself (also about a quarter helium)
We risk running out of cheap helium. But if you are willing to pay infinite money there is near-infinite helium
Well, there is; you can just wait for more helium to be produced underground. That's the same method that provided the helium we have now.