[ARandumGuy]

Most research is funded through grants. Many different federal agencies provide grants, as well as private organizations. When applying for a grant, you have to indicate what you're going to spend the money on. And your grant may be rejected if the organization funding the grant thinks you're not going to spend the money well. And if you can't find someone to give you a grant, you probably can't do the research, even if you have tenure.

There are problems with this system. Researchers often have to spend a lot of time writing grant applications, and grants can be rejected for any number of bad reasons. And there are cases where research was funded that probably shouldn't have been funded. But research funding isn't given willy-nilly to whoever asks, and taxpayers wasting money on kooky ideas isn't a particularly big problem.