It’s very unfortunate and feels like it should’ve been avoidable, especially since China ended up following the USSR’s path of economic reforms and peaceful coexistence with the West. Mao had some pretty bad takes like on nuclear war, funding the Khmer Rouge, Lysenkoism, and the whole “continuous revolution” thing. But of course a lot of the blame also goes to Khrushchev. Imo the right line is that leaders like Stalin and Mao were necessary to safeguard the revolution and eliminate the horrible, unimaginable conditions that the people lived under before they came to power - but once that job is done, then the material conditions call for a more relaxed approach. But unfortunately, neither side saw it that way, and the result was irreparable damage to relations, which broke down trade and harmed lots of people from both countries. Nowadays, China plays nice abroad without caring much about the ideology of their trade partners, and it seems very stupid all around that two Marxist states couldn’t work things out.

It’s kind of a funny psychological phenomenon that people sometimes get more mad at people who broadly share their worldview but disagree about one thing, than they do at people who just don’t share their their worldview at all. I think to an extent the split is attributable to that, but I’m not really an expert on it.