There was a time a little over a decade ago when a good player could sit down at the beginning of a tournament, and most of the people seated with him would be of the "guppy" variety. If there was a good player at the table, you would simply stay out of his way until natural selection got rid of all the fish and only left the skilled players. Today if you take your seat at the start of a tourney, you have a table worth of piranhas staring back at you.
While poker is a very individual game, there is also a great amount of group psychology. The other players at the table are your opponents, but you are also part of a group that you may find, in many ways, to be of special importance.