It seems likely that the world has been using uranium for fuel instead of thorium because thorium cannot be used to make a nuclear weapon. A lesser reason is because thorium has no fissile isotope. A little uranium is needed to start a thorium reactor.
For the United States, thorium is a much safer, greener and much more domestically abundant fuel. It also offers an efficient, cost effective way to expand and decentralize and modernize and green up the power grid.
Investors, start your engines, and or reactors.