Instead, the readily accepted excuse is the problem is just too big to try to solve, so keeping spending and let the good times roll.

It's not that the "problem" (government spending at high levels) is too big to solve. It's that the electorate generally doesn't want to solve it, or even that it's a problem.

Materially reducing spending requires cutting either Medicare, Social Security, or national defense (and probably all three). Voters don't want the government to do that. Oh, sure - there's some constituencies for cutting each of those programs. But they're small and they don't overlap. On the whole, voters don't want those things cut.

Budget hawks like to imagine the government spending tons of money on things that voters dislike or find wasteful. But the truth is that most government spending is on things voters generally like. Giving voters things they like and then passing the bill to future voters is not just something that politicians like - it's something that voters really, really like. Especially older voters, who are higher-propensity voters. Fiscal conservatives can (and do) get elected by convincing voters that a lot of federal spending is on stuff they hate - but then once they're in office, they can't materially cut the federal budget because the pitch they ran on simply isn't true.

Austerity is unpopular. Borrowing money to spend on things voters like is popular. That's one reason why Donald Trump was President and Paul Ryan wasn't.