>We know for a fact now that there are only technicalities like fault tolerance in our way.
We understand the theory behind nuclear fusion, we have plenty of hydrogen, we have the capability to initiate fusion reactions in the lab, so there are only technicalities in our way to powering our electricity needs through fusion. So it has been for 70 years.
Nailing down issues with fault tolerances are a whole lot different than pioneering methods and sciences of uncharted territory. I didn't generalize all technicalities, I specified fault tolerance for a reason, because it's trivial compared to what it took to get to this point. The system works, just not as well as it will take to get to reliable wide spread usage.
It is widely believed that implementing useful quantum error correction (if possible at all) will be orders of magnitude more difficult than what was done so far. To my knowledge, there is no realistic proposal how to implement it on any of the current platforms.
We understand the theory behind nuclear fusion, we have plenty of hydrogen, we have the capability to initiate fusion reactions in the lab, so there are only technicalities in our way to powering our electricity needs through fusion. So it has been for 70 years.