Sit-out or All-in? Leaving a tourney while still stacked

1. If you are in the money just sit out and hope that when u come back u have placed couple pay outs higher.

2. If you think that u can't make it to money anyway with current stack I prefer going all in, Double or Out.

3. lets say there is 500 people left and 50 gets payd and you have under avarage stack. I might just give me chips away by sitting out