Historically, when cattle go bonkers, beef cow guys hold back heifers, grow their herd, drive down prices, reduce the herd, set up a shortage, rince, repeat. I have gathered that prices went so high, so fast, they're just still selling the heifers and making easy money. The "grow herd and create a crash" part isn't happening. It's a rational business decision.
Raising cattle is very hard work. Technology has transformed hogs and poultry, but cows are different. Grass, hills rocks, etc. Now as ranchers are getting older and don't all have the nex generation coming in, that's another reason we aren't building the herd.
And Mexican Screw Worm. It's keeping feeder calves out of American feed yards.
ETA
Politics, tariffs, immigration and the such are likely exacerbating the problem for sure. But ag has enough other bad things going on totally unrelated to this that even in a perfect political environment we'd be in rough shape.