The mind of the low limit SNG player

[M2d]

I just started playing these (30, 50 sngs), so maybe this is the right way to play. also, I don't have much nl experience, so maybe, again, this is correct.

What is up with people going all in when faced with pressure? I'm not talking about late tourney/short stack situations. I'm talking about opening with a normal size raise with a hand like AJ, TT, etc., getting reraised, then deciding to shove it all in?

I don't three bet lightly in these, since I've learned that I will be called (often cold called behind). Here are two examples of what I'm talking about:

I'm on the button with AA. Blinds at 10/15 (just started). Both stacks around the 800 level(I actually have him outchipped by ten dollars). Mid postion player opens for a medium sized raise (60). one caller to me, and I make it 250 to go. folded to the opener who immediately shoves it in with...TT. Did he think that I three bet him with a lesser hand? If I did three bet with less, did he think that the coinflip was worth shoving it in?

example two, same sort of situation opener raises a moderate ammount. I make it about 250 to go with KK. he shoves it in with AJoff. WTF??? This one is even more baffling. He moves it in with a weak A?

Anyway, is this the kind of mindless play that is normal?
Am I correct in continuing to make moderate three bets, or should I start the move in dance myself. The way I figure it, I'm such a big fave over a single raising hand, I want to give them as much rope as they need to hang themselves. However, the penalty for letting them catch up in termination, so I'm not sure it's worth it.