Biggest disadvantage is:

Learning very little and not evolving much as a human being.

Biggest advantage, I  can't say unless you specify something else,

it could go from 'being satisfied' to 'escaping death' and everything in between.

The 'comfort zone' is a terribly generic term, for instance a man could have done

quite a lot of insight to know himself, so he deserves what he finally reached and struggled for,

and calling this 'comfort zone' quite diminishing.

There is no stress in the comfort zone, you're familiar with everything and everything could be expected.But, the disadvantages could be the lack of excitement and the sense of adventure since you can predict everything happens in the comfort zone.Also, when you have to deal with an unfamiliar situation, you'd find it somewhat difficult, so you'd start feeling anxious.

Hi! What is confort zone?

?