If Russia starts WW3, the world will last about two weeks, including the time it takes the top brass to burn through all the people who refuse to push the button and replace them with someone who will.
No.
The incentive is to NOT use nukes, no matter the propaganda. No one can rule over an airless radioactive rock, and no one wants to claim territory that isn't useable. Russia won't start world war 3 because it will 1.) expose how poorly prepared, equipped and maintained they actually are, 2.) they know they will lose. I mean, everyone loses, russia will lose the most because it will be impossible to hide who started it.
As it stands, russia wants a ground war only because putin is a fuckwit intent on things he cannot, will not have.
Yeah, trump is a problem with nukes (because he's obsessed with power he's too stupid to understand.), but it would also be against russia: his owner. He won't be participating. And if he is, it'll be FOR russia, and his regime is incompetent anyway.
Besides, everyone is watching the pentagon right now: the second another high up get bounced and it hits the media it was because he refused to launch nukes on trumps order: the world will be screaming for vonschitsinpants head.
While you aren't underestimating trumps stupidity and incompetence: you are underestimating the rest of the world. I know you don't get to really see it from inside the US, but the rest of us are out here trying to reinforce stability.