More people need ambition to make them comfortable about themselves.
I belong to the smaller group (still relatively big though) of people who prefer a carefree attitude.
When you start reaching certain intellectual plateaux, you need the carefree attitude to avoid a breakdown. Insanity is a coping mechanism to avoid real insanity. The key is to have a carefree basis to which you add "inner-priority" and "intellectual targets" but NOT ambition in terms of being the best or becoming #1.
Ambition of becoming the best at something means becoming the best in a field which already has set standards. This is a problem for introverts (let's call them this) whose targets and goals are usually personal and do not obey external standards. Being carefree helps you be in tune with your internal standards!
To recap. Answer 2 with elements of 1 in the mix.