We literally have a whole-ass G7 country that went 75% nuclear back in the 80s.
No need to run the world: in the last decades, some environmentalists have been lobbying against nuclear energy and in the end, the people in many countries have become opposed to it by fear of it. And that feared is fuelled (among others) by environmentalists for sure.
> Nuclear has never been financially viable
If it's about comparing energies financially (and many other dimensions actually), nothing gets remotely close to oil. But oil is limited and oil is destroying the world.
Also not to forget: everything nowadays depends on globalisation and therefore oil. We like to compare renewables to oil, but we forget that they totally depend on oil at the moment. Without oil, we don't build much renewables anywhere. So an important question is: without oil, do we need nuclear energy or not? I believe we do. I believe we also need renewables, to be clear.