It seems to me nobody is completely sure what the future will hold yet, except that we need to decarbonize energy production. Nuclear still seems like it could be a reasonable/viable/necessary option for decarbonized energy production.
The realistic worst case is that we waste some money building nuclear power plants that operate at a loss and are potentially decommissioned early.
Assuming we collectively have enough money to also keep building wind/solar/etc (it seems like we do!), and the risk of failing to decarbonize remains catastrophic, it's probably a good idea to hedge our bets and try all the viable options.
My guess is that we build a few crappy nuclear power plants with poor economics, learn some really useful things in the process, and then build some better ones with much more favorable economics.