Ok this might be my new favourite conspiracy
Our universe is a simulation created by a group of facists that are using us to research how they can gain and maintain power. If a successful fascist regime takes hold then the experiment will be over and the simulation will be shut off, the only way to survive is to continue to fend off fascisum.
Also it depends on the isotope of uranium. Something you could find naturally isn't too dangerous, but something enriched too be used as fuel or for wepons is significantly more radioactive.