Have I had this wrong for years?

I've long mocked villains for calling flop overbets with a flush draw, but now I'm wondering if I've been the dumb one.

We're in the CO with 120bb and 7♠6♠
2 loose passives who cover us limp. We limp along.
A 50bb stack on the button raises to 8bb. Both blinds fold and both limpers call. We call.

4 players, 32bb, flop J♠3♠2♦
Checks to the button who shoves for his last 42bb. Both limpers fold.

There are 74bb in the pot and we have to call 42bb. If my math is right, we have to make the best hand 100*42/(74+42) = 4200/116 = 36.2% of the time here.

Surely if we don't have 36.2% equity on this flop it's just very bad luck, no?

I'll stop there for now.