It's generally expected that the chip leader and other big stacks play aggressive. They can obviously afford to see more flops and even lose a few hands without it denting their chip stack to severely. Also playing more hands gives them more opportunities to get lucky, hit a fortunate flop, and increase their stacks even more.
My strategy is not to try to out agro and aggressive player. Instead I try to keep it tight and pick my spots. Aggressive players often lose their stacks the same way they built them up in the first place, by being aggressive and taking chances. I will usually wait for a strong starting hand. If I connect with the flop, I will let them try to bully me out of the pot before shipping my stack on them. Keep in mind that we may have differing opinions as to what constitutes a strong starting hand. I'm not talking about sitting around getting blinded off, waiting of A-A or K-K.
While it can be dangerous to tangle with a big stack, they are, in my opinion, the best source for chips. After all, you can't double up through a player that only has one-fifth your chip stack. You're not going to win a tourney by sitting there letting a big stack bully you. You're going to have to take a chance at some point. You just have to be smart and make it count.