Should've seen it coming....

Bad luck or poor play? I think a bit of both....This was my first hand at the table and cost me my buy-in. Finished the evening in profit, though.

Everyone limps to me, one from button. I have A4s, so I limp. Button calls.

Flop comes 2 7 7 with 2 of my suit. Bet of half pot made, everyone calls, giving me the odds to call. Button raises by a crappy amount...2 x min, I think. Everyone calls.

Turn is T of my suit, giving me nut flush. Bet of half pot from same bettor as before, a few folds, I raise him allin . Button calls, he calls.

At this point of my $20 stack I'd put in ~$2, with another $6 to call so I pushed. I was wary of boat but couldn't see him having 7T or 2T or 27. Thought most likely a 67 or 78 suited given the limped pot. As you can see, I don't consider pocket pairs enough...22 would give the boat, but I didn't think of it, so would TT....anyhows....

Button flips over ATo (WTF???), villain flips over....77. Doh!

To be honest, I can't see me folding this. Should I call? Was I just unlucky? I probably played too aggressively but there are loads of times from this position I've seen plays such as the button's, or crappy trips pushing...which I would call with nut flush. At these low levels is it wise to fold the potential best hand or just pay him off? Any help most welcome.