I was in a freeroll recently where a guy had a huge lead on everyone else, and I was moved to his table. He raised every hand, called most shoves with crap (I saw 76o, 29o and others) And had the luck to win most of the flips and times when he was severely behind. It got to the point where he had 4x the stack of anyone else at the table.
Then his luck ran out. He ran into someone's pocket jacks. Then he ran into my AJ. Then he ran into my pocket jacks.
short version: he went from chip leader to gone in about an orbit. I went from low-mid stack to top 5 in the same time.
Now granted, that's an extreme example, but you've gotta protect your stack. That means stealing where it makes sense to steal and not getting drawn into the shovefest unless you've got the goods. If you find you always have someone playing back at your steals, wait until you have good enough holdings to call (not necessarily premium... look at villain's stack size and how they've been playing.)