But if you look at the design you will see that it's much more simple than a PWR. All calculations I've seen puts the cost of construction well below the cost of modern PWRs.
And the cost of fuel is still important, uranium isn't getting cheaper.
Sorry to say this but you have probably been deceived by the nuclear industry. First of all thorium is much cheaper (about 160 times I think), secondly it's far more abundant and third LFTR has a much better design.
The industry dismissed liquid reactors because of the problem extracting weapon grade material. Uranium based reactors where not as safe nor as cheap. During the cold war this made sense but not today.
It has also been about people protection their jobs. The uranium based industry can't say that something else is better because then they might lose their jobs. And who do you think the politicians ask when they want advice?
And the cost of fuel is still important, uranium isn't getting cheaper.