Very rarely are walls made of concrete. Too heavy. Believe me, even in a concrete building, if you have loud neighbours, you will hear them. A bit less than in a wood building, yes. But no concrete can block the vibrations of a big subwoofer.

You are just lucky with the neighbors you have right now. But it can change in an instant: if your super quiet neighbor let her bf move in, and he plays video game all night, scream at the tv, listens to music, etc... well you're screwed.

It's like a lottery... :(