At a fundamental level, our lowest cost energy options are really simple - wind blows and makes stuff spin, dig a black rock and throw it into fire, inject gas into fire, let sun shine on a blue brick, chop wood and burn, make water flow and spin stuff
Now compare that to - keep superconducting magnets 250 degrees below ambient temperature, inject high precision beams of deuterium and tritium into a vacuum chamber, capture escaping neutrons in blankets of pure lithium and berylium. Eventually, capture the generated heat in a primary-secondary heat exchange loop of pressurized water, generating steam and spinning a turbine. All of which requires thousands of highly specialized scientists and engineers to design and operate
I doubt it will ever be cost efficient. And we're not even talking about the cost of fuel. Tritium is mind-boggingly expensive - we need deuterium-deuterium fusion, tritium is just an experimental stepping stone