The premise of this thread is flawed. Teams aren’t giving up more than they ever have. SF is using the 3rd overall pick on a QB, and they gave up fair value to acquire that pick. Top QB prospects have historically been taken at the top of the draft, and draft value charts haven’t really fluctuated much. If the 3rd overall pick was a $20 bill, SF traded them a $10, a $5, and 5 ones.
The OP should really be broken into 2 separate questions. 1. Is the third overall pick too much for a QB? (No) 2. Is what the 49ers gave up to get that pick too much? (Maybe, but it’s more or less in line with the draft value chart).