It's not a marketing problem. It's that the plants are too complex to be properly built and operated.
The Vogtle upgrade has been underway for 6 years and is already 3 years behind schedule, it will have taken over a decade by the time it sells it's first watt to the grid. The total investment over that time will be something like $20 billion.
I can't imagine a scenario in which tying up $20B in capital for a decade to produce 2.2GW of power makes any financial sense at all. With the EPA cost estimate of $1,000/KW for a natural gas plant, you could literally build 20GW of natural gas capacity and probably save 5 years in construction time.
Wind is ~2x more expensive per installed MW, so build 10GW of wind capacity, even with their shitty 30% capacity factors you come out ahead of the Vogtle project.
Hopefully the modular reactors come with much better economics but large scale nuclear is dead for a reason.