Is there? Is this a widely accepted scientific fact? What does this even mean? That you can't get a benefit without a cost? I thought that this phrase comes from economics. I think you're thinking of economics which is... not human biology.
"Infinite, cancer-free lives sounds just too good to be true. Something sounds off about that."
So just accept the fact that we all die and not learn about our bodies? I mean I don't know; some of us value being alive and prefer to stay that way if possible. Do you not also see dying as a problem?
If you were to know that you were going to die tomorrow you wouldn't see that as a problem? Or is it only not a problem if you die at the sort of average full human lifespan age of ~70-80? Why is dying then ok and not tomorrow?