To dream that you are hitchhiking suggests that you have not earned or deserved to be in this position you are at currently. The dream may also be a metaphor that you are getting a free ride. You are becoming too dependent on others and/or using them to get what you want.
To pick up a hitchhiker in your dream indicates that you are taking on too many responsibilities. There is a fine line between helping others and letting them take advantage of you.