Your plan only appears less stupid than Elon's because you assumed Ukraine can destroy Russia's ability to fight and Putin wouldn't use nukes. He has different assumptions, which plan is more feasible really depends on your respective predictions of the future, which is far from certain. This situation is fundamentally different from "arguing that the Earth is flat against all available evidence", where we can be 100% certain due to the available evidence.
There is no guarantee Russia is going to use nukes. There is a good chance they won't because the other nuclear powers have promised things will get much worse for Russia and probably Putin personally if they use nukes. Unfortunately if Prigozhin gets power, he will likely start using nukes because he has no concept of limits.