No sex worker retires Voluntarily.
Their business drops when they hit The Wall, and then they are forced, basically, to give it up.
Girls usually look for Mr Right when they know they are starting to depreciate in value.
Like a used car that needs repair, the owner then puts it up for sale.
If Florence could get her asking price on a consistent basis, she wouldn't retire. But she can't because she is past her Best Before Date.