It's all a matter of their beliefs. Whether that belief is well founded or not - and if they believe instead that their happiness depends on helping others, they'll be equally driven.
Beliefs have the power to create and the power to destroy.
Most of us do not consciously decide what we're going to believe. Often our beliefs are based on a misinterpretation of the past. Often we adopt a belief, we tend to consider it gospel and forget that it's only one perspective. Click the button to the left for a free download.