If winning a SB is your ONLY definition of success, you are in for a lot more disappointing years rather than happy years. Kelly was a FQB. Marino was a FQB. Rivers is a FQB. There are numerous others. None of them won SBs. Some never even got there.
Build your team in all 3 phases. That's the way the NYG's did it. You don't think that Eli is great do you? He is good but certainly not great, yet he won two. Keep building the team every year, including QB, but consider a playoff team or a team that makes a playoff run, not a failure. Remember the Bills of the 90's. Some SB runs, some playoffs, and some non playoff years. What I remember is - it was a helluva ride despite no SB rings.