There have been six presidents who could have addressed this since Reagan. Every one of them shoulders some of the responsibility.

Yes, they should all have taken actions. But also, it is much more difficult to fix something broken once the damage has settled in. I guess none of them was willing to risk the disruption a fix would have caused. And the system seemed to have held up for quite a while. Weren't there some mass firings of ATC personal at the beginning of the Trump presidency?

The bottom line is: don't break things that are difficult or impossible to fix.