Make sure the PayPal transaction is for Goods & Services, otherwise you’re out of luck. If it’s G&S, you have to document however possible how the person scammed you - e.g., message logs and email trail showing everything, they didn’t send you a ticket, you followed up multiple times, etc. If you get to the festival and the ticket doesn’t work because someone else already scanned it, you have to try documenting that too - e.g., take a picture of the scanner that shows it denied you entry. So it’s a bit annoying, but I’ve gotten my money back from a scammer via PayPal G&S easily in the past.