Calling an all in on an open ended straight draw - mistake?

[OneChordWonder]

I play in a local, free MTT league, just trying to get some experience before moving on to bigger and better things. I'm one of the few people there that's really trying to get better. Most players just play (terribly) for fun, but there are a handful of solid but seemingly stagnant players (a few semi pros and dealers mostly) that seem to play only so they can criticize everyone else.

I wound up in a hand against one of these solid players, ended up winning, and have had to hear him insult me over it for the past week, so I thought I'd ask for some feedback:

The blinds go up in these tournaments every 15 minutes with no antes. We were at 200/400 (though it was about to go up to 300/600 within a minute or two) and I was in the small blind with 5-3 off and 4200 in chips (after posting my SB). The villain is on the button and the big blind is a woman who rarely ever raises. There are 3 limpers in front of me, so I complete my small blind. As expected, the BB doesn't raise. The pot is 2000.

The flop comes 10-2-4 rainbow. I semi bluff and bet half the pot, expecting everyone else to fold. It folds around to the villain who pushes all in with his stack of ~6-7000. I have 3000 left in front of me. I'm getting 2.5-1 pot odds, which I know isn't what I need but I've already put in a quarter of my stack and my M will quickly be in the red zone if I fold. So I make the call, the villain turns over K-10, I hit my 6 on the river, get insulted for it, and continue to get insulted for it.

This guy clearly knows a lot more about poker than me, so perhaps I'm missing something. In retrospect, only my semi-bluff seems questionable to me. Any feedback on any part of the hand is appreciated.