That is a perfectly valid photo on the Instagram post today. I just had my wife hold her phone the same way, looked exactly the same. Some people have larger hands than others. If you see some idiot on instagram or twitter saying otherwise, welp, you've found a par -10 idiot, a.k.a. "an id10t error."
Now you can calibrate your idiot-meter based off that idiot and proceed accordingly.
Warning: If you agree with the idiot on instagram, you might not want to walk outside, avoid sharp corners, and try to not run with scissors. Or do. Let us know how that goes, should be entertaining.