Well, no. He was basically under team control for 3 more years (the 2 years remaining on his contract, and 1 year of franchise taggery). Maybe he develops into a QB that doesn't make such a high price tag look crippling to the team in that time. Or maybe he turns into Luck, has a bad hit, and never reaches his zenith. I guess the thing I'm apprehensive about with regards to these extensions being doled out is they're being handed out well in advance of actually needing to do them, which makes them a gamble. One only need look to Gurley last year for a great example of that. Hopefully he comes back as good as before, but maybe he's never the same, less than 1 season after getting his name on the dotted line.
Like I said, I like him, but he's not an elite quarterback yet - he makes too many boneheaded mistakes at crucial times. Right now, he's basically Stafford in a better system with a better coaching staff.
More importantly, look at the teams who have taken home the Lombardi the last 10 years. The one constant is the QB was never making so much that it crippled the team's ability to sign other players. Brady has been playing below market salary forever because his wife, in her prime, made more in a year than he made in a career. Manning was making half of what Goff will be making. Russell Wilson was on his rookie deal, and the Seachickens "dynasty" fell apart the moment he got paid and they had to sacrifice other positions. Flacco was making 4.5 and the Ravens never recovered from his deal. Eli a bit over 6 and the team fell apart when he got paid. Big Ben was under 10, etc. etc. etc.
Consider me cautious, just because we've got a left tackle playing year-to-year, Kupp is going to demand big money in the near future, we've royally sucked at finding linebackers in the draft, so at some point we'll have to poach one, etc. The teams that allocate 17% of their cap to 1 player just haven't shown results.