Ignoring the neverending disputes about whether anyone here will 'make it', what happens if you do? Say your sitcom gets picked up, commissioned and broadcast, then you get an agent and the work starts to pour in.
Is being a screenwriter a job for life? Or do you get chucked after five years and have to go back to working in tescos? What happens when you get old? Is that why a lot successful writers are setting up production companies?