why flopping a boat is -EV for me

[PokerSlut]

Because in the last week, every time I have flopped a boat, somehow my opponent either makes a bigger boat or quads by the time all the cards are out.

I was just playing in a tournament and on the 3rd hand of the tourney I'm in LP and get TT, 1 player limps in front of me, I make it $50 to go (blinds are $10/$15), button calls and BB calls. Flop comes KKT rainbow, and I think "halleluah" and check to the button. BB folds, I smoothcall hoping to build a bigger pot. Turn card is a 4, again I check and button bets pot again. I finally go all-in, buttons calls, and shows me...yes, that's right: KTo.

This weekend I was in a live casino game where the same thing happened. I have 55 in the SB, and end up heads-up against LP when the flop comes KK5. I go all-in, only to find out LP has KQo and hits a Q on the turn. Later in a different card room I get my KK boat (K's over 8's) cracked by someone holding 66 who hits runner-runner 6's to make quads, naturally losing all my chips (again) in the process.

Am I just a fish in these situations? I mean, my choices as I see them are either to go all-in or fold my monster, and I just don't see how folding a boat on the flop can be the correct play here. Please someone explain it to me.