Why am I so dumb?

The title is a rhetorical question, so please don't feel the need to answer it. It seems when I get into the habit of playing poker online, I eventually make the same mistake, and it costs me every time. For more than the past month I have been playing quite frequently online, in various tournament styles and buy-ins, but the one thing that had remained the same was I was only playing tournaments. You see, in the past, just like recently, I have always done well in tournaments, but cash games would destroy me.

The best example of this happened about a year ago. Much like this time around, I had made some money in a Freeroll, managed to get it up to about $75 in a cash game, then got crushed by one hand. My opponent and I were both all-in preflop, and when the cards were flipped over, we both had AA. Like anyone here, I assume a split pot, but when 5 (yes, all 5 cards) clubs hit the table, and my opponent had the Ace of Clubs. This hand is actually where I first thought of the term Double Nut Flush Draw.

Then yesterday, I'm feeling a little bored, but I know I have to leave in about an hour. I hadn't had much opportunity over the past few days to play poker, even missing out on a live game Friday night, I didn't have enough time to play in a tournament, so I decide to play in a cash game. knowing how badly, the play is at the absolute smallest levels, I decide to join a 25/50 cent table. I buy-in for $50, which puts me about average at this 6-player table. Apparently I had not fully learned my lesson.

I'd like to say I'm making a long-story short here, but what happened didn't take too long. Within my first 10 hands, I'm dealt KK in the SB. The player on the button raises the usual amount, I decide to re-raise him, not wanting to worry about him catching an Ace on the flop. He calls almost immediately, so I'm putting him on either a mid-level pocket pair or something like A-Q.

The flop brings K-J-6, and I'm pretty happy right now. I've made top set, so I check, and my opponent immediately raises all-in, having just a few dollars less than I do. No thinking here, I have the nuts, with no obvious flush draw, and barely a straight draw available.

He flips over pocket Aces. He had tried to slow play me by just calling my raise, and likely thought the flop worked out perfectly for him. the turn is, obviously, an Ace, and I'm down to $5 left. I leave the table, turn off the program, consider trashing my computer. 

I turn around and see my wii remote lightsaber for the new Forces Unleashed video game I had recently bought and muttered to myself. "Next time you're fucking bored, play your video game instead of dumping money in fucking cash games!" Luckily, my kids were upstairs.