Why do losing streaks come in sets?

Poker is a skill game, right?
You get your money in with the best hand, and most of the time, you win, right?
If you're 80 percent to win by the river, you'll win four of those five hands, right?
Not if you're on a losing streak.
I've lost 10 percent of my bankroll in the last two days on Hollywood Poker, and though that doesn't seem like a lot, it's enough to sicken me, as if I've just downed a fifth of Jack (Jacks did me in once) and some Coors Light silver bullets (AA loses twice, once to 10,6 os) all at once.
I've only played for real money since October, so on my past losing streaks, they were partly my fault, like losing with a flush to a paired board, losing two pair to a hidden set or going all in with A,K and losing to AA.
And yes, I have made a couple tilted calls, like pushing with J,J and losing to Q,Q or chasing one flush draw down and not getting it.
But I've lost 75 percent of my money on five hands, and on all five of those hands, I was at least a 75 percent favorite by the river, and every time the river fucked me.
It's been a horrible week. Even in the $2.25 tournaments at work, I'm getting spiked.
So my question is, it's mathmatically impossible for "streaks" to really happen, right? I mean, what are the odds, really, of four of the worst suckouts youve had against you happening in two nights? Do I have a shorty memory? No. I can't remember the last time my full house lost to a spiked four of a kind on the river, for instance. I can't remember when A,A lost to 10,6, as I did last night on an all in after he re-raised me twice.
OK, enough whining.
Why does it happen?
Why do we fall into losing streaks after playing winning poker for more than two months? After the game, quite frankly, seemed so easy we contemplated moving up a level or two?
I have some theories based on what's happened the last couple of days:
• Beckoning sirens — I haven't been card dead, as I was last week and only lost $5 in ring play for the week (and more than made up for it in tournament play). My starting hands have been beauties, with full, bouncy boobs, soft, whispery voices and a hell of a tail. AA four times, JJ, KK, QQ, A,Q and A,K, along with other pairs, three of which flopped sets.
I lost with most of them. AA twice when it flopped a set.
It takes amazing discipline to fold great hands, the kind you see in Navy Seals, and when you're losing, the siren's call of "you'll be back to where you were if you win this hand" is just too hard to resist. When you already have a healthy stack in front of you, you can fold almost anything, at least I can. I showed remarkable discipline during my winning streak. I once folded KK two weeks ago because I knew the other guy had AA. He showed them to me after I folded. I folded flopped sets because my kicker wasn't high enough, and every time, I was right. I folded a flush to a full house.
Now? No way do I fold that KK. And it would have cost me another buy-in, and the spiral would have continued.
• Confidence — You can't raise a guy off his hand because, after all, he'll just suck out against you or he's got it already, right? You always think that way. Why stick with a hand? He's got it! My top pair isn't good enough...
Calls or moves we would normally make are not options in a losing streak. Not only do I play like a pussy, I play like a tiny little worm penis, just hoping even a stinky carp will take pity on it and take him home for the night.
• Beaten down — Dieters will call it the what the hell day, a day when they eat that extra cake, drink that extra beer and skip their workouts because they've already done the damage. Mike Caro calls it the point of no return, or something like that, when you've lost so much money that you don't care if you lose another buy in or two.
I have been remarkably disciplined during losing streaks to quit when I'm down a buy in, subscribing to Greenstein's theory that when you quit when you are losing, you're ahead for the next game. That has prevented my bankroll from looking like an extra in "Saving Private Ryan" in the D-Day scene. But I am guilty of tilting off the rest of my buy-in after I've lost a huge pot to suckout. I just bet off the last $6-10 so I can reload. Even when you do that, you've lost a lot more than you normally would.
You start to become the sick gambler in Phil Gordon's book, the guy who not only expects to lose but wants to so he can revel in his own misery.
• Injustice — Surely I've been a good boy, right? I've folded instead of chased, gotten my money in with the best hand and waited all night for this hand to come, so I deserve to win, right?
No. Poker is a cruel, unfeeling game. It doesn't care that the guy called your raise with A,3 and hit his 3 on the river. It laughs at such pain, actually, and asks for another buy-in, like that big plant asking Seymour for just a little more blood. So you continue to call, thinking that the scales will finally tip your way just because you deserve it. In fact, you might even call, saying to yourself you deserve a suckout. It's your turn, you say.
Nobody deserves anything in poker.
Of course, at the end of the night, I won a huge hand with K,K, and finished $25 ahead, so I actually broke even for the night.
Finally.
Guess it was my turn.