Donald Trump cannot tell the difference between a "rival" and an "enemy". This is a serious error. Failure to turn rivals into allies leaves one with no allies, just sycophants. His (and his supporters') attacks on Gov. DeSantis, for example are sheer madness. They're insane, stupid, wrong, unnecessary, and very much harmful to America in the long run.
"Politics is bloodsport", some say.
And that's the problem with politics, and why we need less of it.
What we need here is statesmanship, and I see nobody currently running for national office who really exhibits it.
I would agree with you that Trump is, many times, unduly harsh toward his rivals. He needs to leave more room for mutually beneficial cooperation after he defeats them (because it won’t occur the other way).
OTOH, DeSantis blew an incredible opportunity because of his ego. Had he privately approached Trump and offered him his unqualified support in the primaries in return for being his Veep nominee, he would have not merely saved himself and the Party a lot of time, effort and emnity during the primaries, but he’d have set himself up PERFECTLY for being the POTUS nominee (and likely winner) in 2028. [The fact that both are now FL residents is an easy problem to fix, Trump would simply move back to NY, or to his club in NJ, until after the inauguration. Note that Dick Cheney lived in TX until about 2 days before Bush 43 nominated him; he took a late night flight back to WY and re-established his residency there in one day in August of 2000]. But getting back to DeSantis - he certainly deserves some of the blame for some of the rancor within the Republican ranks...but hopefully he and DJT can put some bandages on their wounds and make this a reality anyway. I think that it would pave the way for 12 years of genuinely patriotic, no-nonsense leadership, not to mention a complete capture of the federal courts by Constitutionalists/Originalists for the next generation.