20 year is the guarantee period for wind and solar. Considering wind and solar are turn key provisioned, it is a reasonable assumption. Also consider than these sites are then habitually repowered. Which in the last 20 years would give you double the power on a site or more.

Depending on the tower choice up to a third of the cost of wind park is in raw metal costs. This does not lose value over all the years. Metal towers are going to be even more common in the future onland (cheaper to transport build and design) and on sea the only reasonable choice.

A VVER-1200 will see like most nuclear plants at least a major turbine renovations in a 60 year range.
Which is a major historic source of failure and costs.
Fuel cost is not as insignificant as we might think.

Remember, as well that for any single provider grid capacity factor is limited by the demand of such a grid. When talking whole grids you are limited to 75% max capacity for all sources combined. If you only have nuclear your 90% capacity factor will drop to 75%ish. This is why for example the UK has so much storage capacity. It's from when their nuclear energy was building out.

Also look at when construction even serial in Nuclear started to fail. In france this was the N4 generation that was designed in the 1970's. Since then costs and complications have arrived. i.e. to be safe the plants have become more complicated to build.

EPR's are terrifying in their complexity and the 11 year death march the European builds are on. The chinese build them but with closed books and unknown oversight. They are not going to build more of this model.

Westinghouse could not build it's design either.

VVER-1200 was specced to be build in under 5 years. It also took the Leningrad builds double that time. Novovoronezh-1 took 8 years, but -2 which is supposed to be faster took 10. What is up with that.

Also remember that Wind and Solar are often reported full project costs, including transmission, with repairs etc. . Nuclear is often only the reactor and transmission and other costs that are part of the project are not reported.

For wind if I have site and 10 billion, next year or the year after it's full and on schedule. For nuclear I might have something next decade.

Take a VVER-1200 at 90% capacity costing 10 billion USD
10 billion / (1200 * 0.90) => 9259259
Watney extension number, a current gen offshore
3 billion / (659 * 0.45) => 10116337

Wow you say, look nuclear is at least 10% cheaper! Yes, but your financing costs are double that for wind. Your running costs are higher, and you don't have a transmission. You can of course complain that I added 1.4 billion to the nuclear story (costs from the finish VVER-1200) project. Taking into account the finish VVER-1200 first paper work was granted in 2010 and is likely to be operational no earlier than 2028 the then year USD will easily make those numbers.

So in the best case nuclear is cheaper by 30%. Worst case it is 300% more expensive.
What will you do if someone builds wind next to your nuclear powerplant? They have 8 years of profit before you turn on.
Will you be able to sell your electricity? Will there be a market? i.e. you are building expecting an aluminium smelter as customer but it went bankrupt in the decade that you are building.

Nuclear, risks, risks and risks. For insignificant potential upsides on the market.
Wind, known quantities, insured, guaranteed, with fixed costs and often known profit margins.

This was too long ;)