It's funny. Two years ago, Denver signed 37 year old Peyton Manning, drafted Brock Osweiller, and were lauded for having a present and future plan at QB.
Now, the Patriots draft Jimmy Garoppolo to backup 37 year old Tom Brady, and it is a wasted pick.
Brady will start in NE for as long as he is the best QB on the roster. That will not be forever. At some stage, Brady is going to be the Bruschi treatment. Belichick is going to call him in and tell him, "you don't got it anymore, you're not making the team, so do you want to retire, because I'd rather not have to cut you." That's reality.
Garoppolo has potential to be a very good starter. He is smart, has a strong arm, and was productive. He needs time to learn the pro game, and this situation will give him 3 - 4 years of time. Will he make it as a starter? 50/50 bet probably, but if he wind's up Brady's successor (or guides the team to some wins during a Brady injury), people are going to be calling this a genius pick.