Look around the room.

The reason why NASA ended the Apollo program is because the American public 1) was never as committed to Apollo as younger people seem to believe they were with most people being indifferent to it and plenty of people being outright against it as wasteful, and 2) even the modicum of support it had on the Apollo 11th landing was gone by the next mission. Famously, Apollo 13 was notable for regaining the attention of the public, which it almost certainly would not have had if it weren't for their lives being on the line.

The public has almost never voted for more funding to NASA. The Kennedy Administration put a shitload of money into NASA hands, without real public approval, for geopolitical goals. It was never for public anything. The public just cannot be assed to spend even a few dollars on things they don't like, and they've never cared for generic space science.

The general public can in fact do whatever they can manage to fund, including through enormous debt, which is how we spent like $40 trillion on stupid wars in the desert for no reason. I was never really in agreement with doing that, but for some reason such a suggestion was "Unamerican", as claimed by the very people bitching about the debt right now. Who just so happened to be mostly the same people voting on doing those stupid wars.

It doesn't matter how many games you want to play with how "the system" makes it hard to vote for the right people, or how the incentives are constructed, but even in such a system, the Trump power bloc is still based around voting people out if they get in his way. The power always comes down to voting. The people in our government do all the shenanigans they do because it's how you capture the votes. They pander to giant businesses because those businesses pay for their political ads, which always go up in price so that only the largest businesses can afford to control them. But politicians do it because those ads get them the votes. If just doing their job better got them more votes, they would do that, or be replaced with someone who would.

The powers that be are the voters, with caveats and nuance.