Tournaments are different than ring games. They require different strategies. Some players who win in one lose in the other because they don’t see and adapt to the differences. A very successful ring game player once told me he plays Stud8 exactly the same in a tournament as in a ring game. If ever there was a game that should be played differently in the two forms, it is Stud8. (See Tournament Seven Card Stud High Low) But he played them the same -- and won big in the ring games and stunk in tournaments. This inability to adapt is what keeps a lot of winning ring game players from winning in tournaments.
One bedrock principle of winning ring game play is that you need to be properly bankrolled. If you have the bankroll, correct play will win out in the long run (barring super-extreme bad luck). But nobody is ever adequately bankrolled in a tournament. When you play 15-30, you never have $10,000 in chips. More likely you have $800. That surely is not an adequate bankroll to absorb normal fluctuations. You should not play like you do have an adequate bankroll. You have to adjust. Adapt, or die.
At the same time, some winning tournament players lose in ring games... often because they can’t stand to lose a pot. In the critical stages of tournaments, you have to win a high percentage of your pots. You have to try really, really hard to win many of the pots you are in. But in ring games, the ability to sensibly surrender pots is a great skill.
Ring game poker versus tournament poker is the difference between dedication and inspiration. Ring game play values steadiness, repetition, an even keel, consistently making the mathematically correct play, showing up day after day and playing better than your opponents. Tournaments value "seizing the day." The ability to inspirationally find a successful play in critical situations is far more valuable in a tournament. The General you want running your army during peacetime will not necessarily be the best General in the heat of battle. The best movie director of a tender love scene may not be the best to blow up Mars. Different skills are required.
To think that a person who excels in one arena is "better" than a person who excels in another is hopelessly missing the point of the game. Who is "better": Michael Johnson (a sprinter) or Lasse Viren (a distance runner)? Is winning a gold medal in the 100-yard dash "better" (or worse) than winning a gold medal in the marathon? The whole notion is just nonsense.
Truly outstanding players will adapt to whatever circumstance they play in. Great players can win tournaments and win in ring game play by understanding the differences and adapting.
The majority of successful tournament players are successful ring game players who put in more hours at ring games than tournaments (though less time in ring games than professional ring game players.) Many players who play primarily in ring games are very successful when they do play tournaments. The idea is to play good, play correctly, any time you play poker. But sometimes the correct play will be very different depending on whether you are in a tournament or in a ring game.
Winners in ring games win most days. Winners in tournaments lose 75% (or so) of the time. A definite tournament skill that many ring game players simply can't master is the ability to lose most days. They can't see the long run of tournaments, so they avoid them. But there is just as much of a long run in tournament poker as there is in ring game poker. It merely takes different psychological attitudes to excel at each. There is no reason at all that one person cannot succeed at both. You just have to see the differences, understand and accept the different ways money comes in, and then play correctly in the different situations.
The secret to winning at tournaments and at ring games is simple: play good. Just don't always play the same. To everything there is a season.