Where did this fallacy come from that good teams don't spend money? Yeah, a team bargain shoppong can win a SB when they've gotten lucky in the draft a few years straight, and the cards fall just right.
"Drafting better" is easy to say. But even well run organizations miss because even your favorite pet cat can flame out.
That's what FA is for, like the Broncos last season, or the Patriots the year before.
The other teams that are now running the NFC or have for years either stocked up on defensive talent for years and years with top 15 picks (niners, Seahawks, panthers) and got incredibly lucky with later round picks (Sherman, Wilson, Norman, chancellor, etc). Arizona and Seattle have both spent money in FA as well. The year the Seahawks won the Super Bowl they spent a ton on their DL.
The Patriots have the best QB in the league and one of the best coaches of all time, and even they spent money on their way to their last Super Bowl.
You don't get a trophy for having the most cap space in the off-season. And a team that forced the least TO's in the history of the NFL while unable to win a game without their starting QB shouldn't be parting themselves on the back about how "smart" they are because they didn't spend money on impact players when they very well could have.