Most Interesting Lost Ever

I'm pretty used to bad beats like people catching their Ace when I have pocket Kings or losing to a a flush draw, when I have a decent hand like trips or two pair, but what happened last night is totally new.

I'm the big blind with 5 people left playing. Two people fold, then the person dealing raises a decent amount (I think it was 3x the blinds), the small blind folds and I call the raise with pocket 7s because I believe he's just trying to steal the blinds. The flop is 10 4 6 all different suits. I bet high and I'm called, the turn is a 7 and I make my set.

I'm wondering what the other guy could have since he called my bet instantly after the flop. I thought it was a high pocket pair like Jacks or maybe he had a 10 with a high kicker. I go all-in. The guy calls immediately and shows me his 3 5!!!! He made his goddamn straight with that seven!!! The river brings me nothing and I'm out of the game. Why the hell couldn't I lose to something better than 3 5???

4 hours later the game ends and I'm a little happy since he didn't win. The guy that beat him caught 8!!! yes 8!!! full houses during the night. It was a very odd night of poker.