Some people bail quickly. Very quickly.

Most people try and give a position a chance to improve. Some people are more optimistic than others or are, perhaps, less confident in themselves so wait longer.

Working freelance, I have always seen the job out. Even when offered something else or feel that I am being taken advantage of I still feel loyalty to the project. It may seem daft but I feel it is the level of professionalism that is required of me.