It may imply that, if staying in your comfort zone makes you happy. Everyone comes with a different outlook on life. For some it's important to create startups. For some it's important to have a stable income, pension, benefits, etc. There is no universal truth as to what one should do in life to be "successful". I have a feeling that if Mother Teresa and Warren Buffett were transposed that each would be unhappy.

What is important is to find out what balance of friends, family, work, charity, money makes you happiest.

It is very unlikely that you will always be in your comfort zone. When you ask yourself this question ever day, "Are you happy?", sooner or later you will find yourself replying back "no". Then you will need to change something to make yourself happy, the action of changing something will take you out of your comfort zone.

I try it often, it works, but you will need to be honest with yourself when you answer this question.

Depends; if you like being in your comfort zone and can maintain that indefinitely whats the problem?