Nearly everybody in poker is a relatively bad player. The only ones who can truly claim to be good are those very few players who have managed to stay at the top of the game, making money at all games at all limits, for a considerable period of time.

Outside of this select group, everyone has some kind of obviously exploitable weakness (although you may well have more weaknesses yourself, ones which make you unable to exploit their weakness - even if you can identify it).

Understanding where you are in the poker world is critical to becoming a profitable player, as knowing where you currently stand is critical to a whole manner of important poker decisions, ranging from table selection through to bankroll management.

If you think of the very lowest stakes games, most of the weak players in these games have so many weaknesses that realistically they should not be playing poker for money at all - certainly in terms of looking at it as a way to turn a profit (most of these players are there much more for the recreational side of it anyway).

These player's money is steadily hoovered up by other low limit players who have just about cut down their own weaknesses to the point where they are able to beat the very lowest players. Despite being able to win at the lowest stakes, these low stakes winners get annihilated at the higher levels, and many will lose all of their low stake profit plus interest taking reckless shots at higher stakes.

This effect is prevalent all the way to the very highest limits, with an endless stream of players taking shots at the bigger games to see if they can cut it with the very best, with most losing and dropping back down the stakes or going broke.

Understanding that you can currently beat game a), might be able to beat higher stake game b) with some experience and hard work at your game, but that you have no chance at very high stake game c) at the moment, is crucial for maintaining your bankroll over the long term.

Poker is a game where you have to always be learning and improving in order to consistently win, and understanding where you are at the moment, is just as important as understanding where you want to go in the long term.