It comes down to cost.
I’ve seen some massive projects around the world that purport to get solar power at the lowest —at around .02 @kwh usually, the numbers on the big solar farms in the desert come in around .035@kwh.
The first-generation fusion plants promise to deliver electricity at .01@kwh.
Fusion will at some point be the dominate power source but that’s 50 to 100 years away we need to get mining the moon up and running for the helium 3 needed for fusion. Elon is working on the moon mass balance part Starship with 100+ tonnes payload could in theory come home with enough Helium 3 to power the entire world for a period of time like years worth on a single Starship.
Using deuterium (D2) tritium (T3) fusion you need T3 not easy to get it’s radioactive with a 13 year Half-Life. You have to make it by bombarding lithium 6 with neutrons at.high energy...like in a fast spectrum nuclear reactor. Or you have to sacrifice neutrons from your fusion plasma to breed the tritium in a lithium blanket around your plasma. That significantly increased the Q factor for net output. The other other choice is out uranium around your fusion plasma and then lithium around the uranium. Now you have a fusion fission.hybrid that turns uranium into PU239 and copious.neutrons that makes everything around it fiercely radioactive by contact including the lithium you want tritium from. At this point you should just breed PU239 and feed that to a dozen large gigawatt sized normal reactors using the fusion only as the neutron spark plug at the core of the cycle.
CANDU reactors today put out 1.8 cents power to the plant gate half the cost of PWR tech. I will be shocked if in my lifetime fusion is under that price.