Tournament poker is a marathon, not a sprint. The end result of this race is to be the last person standing with all chips at the end of the day, and how we get there is the question. There are as many different approaches to a tournament as there are personalities playing the game. While nobody is going to say no if offered the chip lead in a tournament, there are benefits of playing with a mid-sized stack in front of you.
Players with the short stacks are the feeder fish of the tournament. It is almost as if they are walking around with a "kick me" sign on their backs. In other words, they tend to get attention from the large stacks at the table. The folks with a lot of chips also have a target on their back. The other big stacks want to take them down a few pegs and limit the number of power players at the table. Middle stacks can just fly under the radar for a little while in a tournament.
Good, sound poker will get you through the early rounds. Your stack won't grow fast, but you will tread water with steady growth as more aggressive players are gaining and losing fortunes in the blink of an eye. Of course you can't win being second best, but the conservative play sets up a table image that can be exploited later in the tournament.
When you get to the latter stages of a tournament, chances are your opponents will be aware of who you are and how you have been playing. This is the time to change the way you have been playing and suddenly become a loose player. There will be early success, especially against people who have faced you before. You will have conditioned them to fold in reply to your raise, this will serve you well at this point in time.
Playing a conservative game with a mid level stack will help get you to the late stages of a tourney, and that is all a player can really ask for. Getting that far will make you a legitimate threat for a money finish. In addition, the table image you have cultivated will help you make up ground on the big stacks when you unexpectedly become someone different. When the blinds become debilitating though, all bets are off and it is anyone's tournament.

