Some degrees are less in-demand (at time of graduation) economically, but a well-educated populace that can apply critical thinking and remember lessons from history, can be its own reward. Notably, pushing for a population completely lacking these skills is an excellent way to topple a democracy over time.
I see your point on broader benefits, however, those are largely speculative while a shortage of e.g. doctors has very direct and concrete costs to the society.
On prior point regarding spreading risks - would you say government should bail out failed entrepreneurs? Because that is very similar in principle (taking risk, benefit for society)
I'm not saying failed entrepreneurs should be bailed out, even if (through bankruptcy proceedings) they de-facto are. To your point though, they're given tax breaks by my government [0], which aligns with the goals we seem to have agreed are important and good for society at large.
Small businesses are given assistance when starting out and financially vulnerable; financial assistance that is paid for by all members of society, as we all reap the benefits of a stronger economy when they succeed. I'm not sure how one defends not extending the same courtesy to students.
I think that's fair that risk should be more spread. Comes at a cost of people choosing degrees more frivolously though and wasting their time and everyone's money