But apart from the part that's useful for nuclear weapons research, we've barely given it any funding. The idea of "we could have useful fusion reactors in 30 years" always came with the sentence "if we get the funding to do it".
There's this [1] famous graph comparing US research spending into Fusion, compared to 1976 predictions how long it would take with different budgets. According to that, the US funded fusion below the "not enough to ever get it done" budget. With that in mind, we have come remarkably far.
That famous graph was for a crash program for tokamaks, and it was predicated on tokamak physics working much better than it turns out it does. If that program had been funded it would have been a guaranteed failure. It would probably have been a failure even if the physics had been favorable, for engineering reasons that didn't become a point of public controversy until the 1980s.
Also, I think you have causality reversed. Fusion isn't remote because of lack of funding; rather, funding was low because there weren't stakeholders pushing for it, and that was because the stakeholders didn't see any value coming from it. For example, all the reactor designs utilities had been presented with were not things they had any interest in building, they were too large, complex, and expensive.
Solving hard engineering problems is expensive. You have to put lots of money into it. Say, 30% of the funds invested by VCs in jitney cabs and collectable JPEGs.
