We are all self-employed. One in six of my Linked-in connections has changed jobs in the past year. Once upon a time, people worked 35 years in the same job. And changing jobs was seen as a sign of instability and weakness. After all, a rolling stone gathers no moss. ( And who likes moss any way?, apart from snails maybe?)
We punch our card for our boss just to confirm to all that we showed up. And our work tells if we really showed up. Seth put it nicely this morning in Can I see your body of work?