Oh wow but a GPS jammer is okay so someone could get lost and possibly killed, or even crash a plane?
Though most GPS jamming is by countries at war. Russia has a large GPS jamming operation around Ukraine, and this often affects GPS in other parts of Europe as well. I have no information, but I would be surprised if Iran wasn't also jamming GPS (off and on depending on the current state of their war). You can safely assume every military in the world has some GPS jammers that they have plans to use if it makes sense to them.
FCC will hand out fines if they can find the owners. Reading through the comments here about the hardware size and capabilities nowadays for pretty much off-the-shelf solutions, it is not a far fetched thought that an adversary can plant thousands of jammers in dense urban environments and then turn them on whenever they want to. Imagine what a blanket jamming can do in NYC airspace.