I think the difference is that with cancer cures we mostly care that it works as proved by trials, and understanding it is a bonus.

Up until now the prize in pure (as opposed to applied) mathematics was the _understanding_ and the machine can't do that for you. What does it mean if we get "super powered alien maths" but humans can't do it? It's like inter univeral teichmuller theory but imagine if Mochizuki was right and it came with a lean proof?

It was the understanding for some, and the result for others. Math is going to bifurcate along those lines. Many are the builder type who use math for a purpose. To accelerate an algorithm, to improve the numerics or convergence of a computation, to verify statements about real things, to use it in angineering applications, etc etc.

In my view, over the last century, math has turned into an intellectual analogue of extreme bodybuilding competitions. A navel gazing runaway optimization in making useless stuff just to demonstrate cleverness. That's fine, why not. But society has no obligation to fund that, just as it doesn't fund other extreme hobbies. Ideally if we ever get something like UBI, math can be still their hobby.