A bad call, or a player calling your made hand with terrible odds and hitting his drawing hand will decimate your stack, even if you were playing well.

Sounds like when you get a big stack you start playing scared... if that's the case you should get up for sure. What difference does it make if you get drawn out on with a big stack vs getting drawn out on when you just sat down? Sure if you both have big stacks there is more risk, but you want other big stacks making dumb calls against you, that is how you make money.