When to move down?

[boudge7]

A lot has been posted regarding when to move up levels, but at what point do you realize that you need to move down, or you've reached the highest limit you can be a winning player at? How big of a sample size truly tells you that you're just not cutting it at a given level. Further, is it possible for all players to get the point where they're 8 tabling the $200's? Is it to say each player needs a goal (i.e. a 10% ROI at the $100's, or something to that affect)? Those you out there that have thousands upon thousands of games, why are you playing where you're playing? Is it comfortability? Is it bankroll? Why haven't you changed the level you're at? Answers to any or all would be much appreciated.