It's true. As the best team in the league, you need to retain your young vezina goalie. You don't want to be a Cup contender and fall short because your goalie is michael leighton.

But it is still a big risk. Even when those star goalies had vezina seasons, they didn't win Cups (except MAF). On the other hand, niemi, crawford, murray, and binnington have all won on entry level deals.
I think MAF and Quick are the only high paid goalies to win a Cup in the past decade.

FYI, The two highest paid goalies in the season they won the Cup in the last decade were Braden Holtby and Tim Thomas.