All the opinions make valid points. Everyone has to decide for themselves. Machines need maintenance. BMW makes great machines. To have a car with this capability and not expect to fix it is naive. I'd take my chances with the M3 over many other cars that are typically driven hard.
Stories of 300,000+ miles on other M BMW's, albeit with proper maintenance, are comforting. I would by the M5 from the guy in the video who bought it new for example. But I would not by an M3 with 50k if I found videos of it doing burnouts and drag races, or just too much evidence of previous modification.
Also, my 08 M3 get's the "looks brand new" comment all the time.