As an ageing Gen-Xer I have never understood why we cozied up to the ChiCom horde. To me it makes as little sense as if we'd set up a Most Favored Nation trade status with the USSR and started buying their cars, clothes, and transistor radios.
Nixon's going to China while China is still giving artillery shells, missiles, and fighter jets to Vietnam so Vietnam can murder American boys in the winding down war there was absolute lunacy, and don't even get me started on the buttfucking that Taiwan has gotten. I'm sick to death of having watched every president kowtow to the PRC because "hEy At LeAsT tHeY wErEnT ThE sOvIeTs" no they're fucking worse because we didn't build factories to create sensitive electronics in the USSR. We did, in China, and guess what, copies of same have modernized Iranian, North Korean, and even less savory countries' military apparatuses.
The USSR was motivated by a political ideology of "Everybody! Let's SOVIET!" and on the face of it they had to know that was never going to win. They went from Hapsburg adjacent swampy plains with delusions of grandeur to totalitarian superpower to second world has-beens in the space of 75 years. Do they suck now? Unquestionably, but that's another discussion entirely.
But the Chinese? The Chinese are hellbent on consuming the fucking planet like locusts. Their Manifest Destiny is "Everyone is subservient to us by 2100, regardless of what government we have". They are an actual bughive. The world's biggest mistake post WW2 can be argued but I'd say one of them was not letting that country collapse into a bunch of competing Asian backwaters. The world would be far, FAR better off.