It's a never ending hole. Do you rent car when you're shooting because it's not that expensive to rent a car instead of using your own car? There's always a better car you can rent, so you might as well, right?
If you're asking the question of "what camera should I use" you're lacking in experience on set. You'll be better off spending the cash on props, wardrobe, set design, better locations, a dolly/crane/drone, more lights, an extra wireless, better crew or even hiring extras. Hell, keep the excess money for your next shoot or keep it as a contingency in case something goes wrong. I suspect it'd be better spent on buying a case of beer for the wrap party.
There's always upgrades. There's an upgrade every second week. Don't get suckered into thinking you need more and more gear if what you have is more than sufficient.... or you don't know if you actually need better to get the job done.
Focus on telling the best story you can. Don't get bogged down in worrying about incremental differences in equipment.
