1) Pu is
incredibly toxic
2) You can make nuclear bombs out of it. If it's too diluted, you can purify it with normal chemical processes and then make your bombs. It's not like uranium where you need a monstrously expensive isotope separation process to get the fissionables out.
3) Even if ransomware gangs don't get their hands on the Pu, billionaire tech bros with nukes sounds dystopian enough in its own right.
4) Even ignoring the weapons proliferation aspect, startups building Pu-fueled power reactors seems like a dumb idea. Thorium-molten salt may be a little harder but holds lots of promise. It's being built in China now.
