From No Limit Hold 'em: Theory and Practice by David Sklansky and Ed Miller.
Concept No. 57: Don't be fooled by players who have giant amounts of cash in front of them.
Sklansky and Miller suggest in their discussion that players who buy in for exorbitant amounts often do so in order to trick other players into thinking that they will be willing to lose their entire stacks, thus enticing these other players to play too loosely. This doesn't fit my experience at all. In my experience, players who buy in deep do so either for mundane strategic reasons (they feel they can outplay the other players at the table with deep stacks) or in order to gain a psychological advantage (either they want to intimidate the shorter stacks, or they want to avoid feeling intimidated). I don't think anyone buys in deep in order to trick players into gambling with them more.
The issue of whether it really is strategically advantageous to buy in deep is something I've addressed in posts a few times before. While many people are intimidated by playing against bigger stacks and believe they are at a disadvantage, I believe it is actually an advantage to have a smaller stack at a full table. It's possible that in certain games you will have higher expectation if you have a big stack, but this is only if you are far superior to your opponents. If everyone plays about the same, players with smaller stacks should be expected to do better.