That there, was what caused the accident more than hamilton. You could see verstappen steer left for a split second, but straight away he steered right again and fractionally cut across hamilton, albeit unintentionally.
And it's that that leads me to believe why hamilton was given the 10 second penalty. Verstappen paid for it by being out of the race = no points.
Thanfully, neither of them were badly injured, but as we know, F1 is all about timing and fractions, thousandths of a second, and it could be death.