Why are some mirror-less owners such...dummies?

I can live with the buyer of a $6000 DSLR not knowing how to use it, having more money than knowledge, but a mirror-less buyer who cries that he can't properly capture indoor karate lessons shooting at 1/125th and 3200 ISO, who should have bought a Nikon D500 and a fast FX lens make me ill. Mirror-less are great for a lot of things, but following fast action in low-light is NOT their forte. That's the domain of D500's, D5's and 1DMkIv's with suitable accompanying lenses. If you plan to shoot that, don't spend $2000 on a mirror-less, get the $2000 DSLR. But more than that, this isn't news to anyone who has done even a small amount of research.