A 10.5 is only normal to arm-chair racers spoiled by the glut of 600+hp factory cars. Even 10 years ago, those times were reserved for hyper-cars, or stripped-out hotrods which were towed to the track.
Even today it's impressive to see a street car run under 12s. On a given test and tune night, I'll see maybe one out of 50 street cars run sub-11s, and they're always obviously modified.
You claim it isn't insane, yet your example is BMW's fastest car. I'll throw out another Definitely Not Insane Car running a similar time: Ferrari 488 GTB.