"they don't make the same mistakes twice."

But they do. Even if we limit ourselves to post-1949 China.

Once Mao died, the Party decided to never allow a single leader to arise again, and switched to an oligarchic model. But Xi was able to break that system and once again you have a sort of cult of personality with One Dear Leader at the top, although we have to admit that Xi is a lot saner than Mao ever was.

But the negatives are once again rearing their head, worship of a single person, personal loyalty triumphing over competence, and the Chinese economic machine, subject to whims of a single person, seems to be slowing down.