Maybe America should consider doing that. South Korea has jailed four ex-presidents so far, and will likely continue to do so in the future. Somehow the country is fine. If anything, I think it helps establish the notion that nobody is above the law.
(Not saying everything is great in South Korean politics, of course. Ask any South Korean, and they'll argue to death that half of South Korea is selling out the country. The only difference is which half.)
Being a war criminal
If it allowed prosecution of people for being political opponents, sure, but that’s not the issue. (And its interesting that almost everyone making this case has, both before and even after making it, argued for the prosecution of their political opponents.)
OTOH, allowing political opposition to be a “get out of insurrection free” card, is an obvious existential risk.
> Nick Land puts it well: “If Trump is jailed, every US President will be from this point onwards.”
Even if I agreed that was true (which I don’t), it would be a lesser problem than “if an attempted autocoup is unpunished for Trump, the next US President elected freely will be the last.”