I didn't hear the interview, but it is a credit to Catriona that she was prepared to be interviewed on the radio about the sex industry. I'm not sure how relevant her income is, tbh, as long as she doesn't have to hand over half of it to a pimp/agency.
It's also quite possible that the figure of €40k per annum is accurate, after deduction of all her business costs, including advertising,hotel/apartment accommodation, travel, clothing, telephone, hairdressing, make up, condoms, and other assorted gadgets.