If student loans could be discharged banks wouldn't lend to unworthy creditors. Because the bank gets paid back written in blood you might as well just provide as many as people will sign for. Doing useless degrees in particular seems like a better deal from the financing side. If this were normal debt and the degrees people got were useful, maybe yes.

Throwing money at the first does not preclude throwing money at the other three as well.

It's not one-or-the-other. This is still America; you'll get both. There will be more wars, more corporate tax breaks, and more bank bailouts. You can count on that.