How much money does a professional sports referee earn?
Ask someone at the reference desk of your local public library for the Occupational Outlook Handbook. It lists all kinds of information you would need to know,(including the salary) of just about any occupation you can think of.
Yes they could, but when they got the result they will be DQ ( disqualified). But if they told the referee first, they will just let them play but they won t be in match. But the pros won t do like this because they knows the rules. And playing amateur tour does not earn much money than the professional tours.