How do you guys go on such insane downswings?

I honestly cannot understand it. Every day on this site I see some story about a 200+ BB downswing. How does this happen to so many supposedly good players? Do you tilt away 100BB? Start playing scared? Exagerate?

I've played poker for about 6 years and had one downswing of over 150BB. My pro friends almost never have a 200+ downswing (i.e., like once a decade). I understand variance, and I play a LOT. Maybe I am just insanely lucky, or maybe I just don't tilt away money when I am running poorly. But it's gotten to the point where I barely come here anymore because of the depression/paranoia that all the downswing posts threaten to generate. Before coming here, I was honestly under the impression that a really bad downswing almost never happens to an expert player, and that when it does it's really major stuff (like Doyle's).

Anyways, I'd like some thoughts on why do many players on here seem to hit major downswings so often. I have a theory (being too tight and slightly weak magnifies downswings greatly), but I'd like more opinions.