Sounds like the people that put plastic covers on their very luxurious leather sofa. You got a nice car so you can enjoy it, why are you spending your time in a tin box ???!
I can totally understand having a commuter and a track/fun car, as many fun cars are poor at creature comfort. That is not the case of the M3.
Devaluation is the biggest hit you take on a car like that, not gas and maintenance, so even financially, ownership makes no sense if you never use it, as not using it bumps the per-mile (per hour of enjoyment; the only metric that matters) price to horrible heights.
Your car, your life, but hey, you asked