As an attitude, scepticism is that which calls into doubt something that comes toone's attentio nin some unacceptable way, or that is unacceptable but possibly believable. So why have such a reaction?
Scepticism about what others say is often inevitable given that you have your own beliefs already about so many things. It may assist in finding the route around it's future object, or conversely, it may be the cause of those later things - a struggle to avoid that which is caused by the struggle.
In any case, it allows one to understand another position without adopting it. And that is one route to getting along with other people.