But they know you know they're three betting you light so the question is do you know they know you know they're three betting light and if so do you really know what you think you know.

I dunno

Im not taking about being an underdog going to the flop... i mean being dominated throughout the hand!

I mean u would fold A2o in the big blind against a raise and two callers. Even though u´re never an 7-1 underdog. U would fold because u lose money throughout the hand being easily dominated.

I don´t get why that principle couldn´t aply to this hand?

This is just a hypothetical question though. Because if its true that it would be less -EV to fold against a reraise then calling the 3-bet then thats just a reason u shouldn´t raise it in the first place.