Pretty damn interesting article on the psychology behind enduring bad beats and what-not here, at CardPlayer.com:
Being Beyond Pain by Lou Krieger
I'm always a sucker for stuff like that, as I find the psychological underpinnings of poker endlessly fascinating.
I forget exactly where I saw it (somewhere out there in the poker blogsphere, I think a thread on 2+2), but there was an interesting related discussion, touching on the long-term effects of playing poker and serotonin levels in your monkey brain. The basic theory was that when you first start playing, your brain supplies you with a nice jolt of serotonin when you do well, making you happy happy. So while you also suffer the inevitable bad beats and suckouts, the feelings of anger and depression caused by them are always mitigated by the serotonin-fueled joy when you win.
The problem is that you start developing a tolerance to the happy happy serotonin producted by winning at poker over time. What used to bring you great joy only produces a half-hearted golf clap in your brain. At the same time, though, you never really develop a tolerance or immunity to the pain caused by suckouts and bad beats. So you continue to get the anger and rage and depression, when the cards run cold, without any of the happy happy upswings. The real danger is that you start pressing too hard, playing limits that are above your bankroll in a misguided attempt to recapture the magic you used to feel when raking in what seemed like big pots at the time.
Forgive me for likely butchering a lot of that, but it rings pretty true to my monkey ears. I fall prey to this more on the casino side of things, not content to book a nice little profit of $75, pushing harder, and harder, and harder, until, well, you know... But I have to admit to occasionally experiencing the same at the poker tables, to a lesser extent. I'm pretty good at keeping it in check, and being mercenary and focused about why exactly I'm playing, but it is a hard battle, as some of the simple joy leaks away, and you sit there pressing clacking buttons, over and over, doing nothing but capitalizing on the general ignorance of other people who push the same clacking buttons, just not as optimally.