With the amount of money that's involved, it's major! He'll be in Federal Prison, not a local jail, for a bunch of years. Then he'll have the registered felon monicker around his neck forever, & that'll make life for him more difficult. Good luck finding a good job with that.
I hate thieves. It's not just money that gets stolen. It's trust in everyone that gets taken too. & he being considered a friend? That's salt in the wound!