There certainly are two camps when it comes to daily driving an M3. I didn't buy my M3 to look at it. I bought it so that I'd have something to drive every day that I LIKED driving. There is no doubt in my mind that it is significantly cheaper to take the depreciation on my e90 than to buy and maintain a second car. I put about 25k miles on my car every year. It costs me about $7k over two years to put the extra miles on my car.
I'm on my second "beater" M3. And, No; I don't care if the prissies out there would never buy my car used.