You will hear people who say “I’ve been RVing for 20 yrs and never had one”
Having one is like insurance, you hope you never need it but you should pay for it anyways.
The answer is: Yes you need one, if you don’t use one, and the campground pedestal gets a surge and pushes it to your RV, the cost to replace your appliances will be in the thousands of dollars and hopefully it does not fry all of your wiring and cause a fire.
I run both a surge protector AND an EMS (see link to blog post below on differnce), surge protector to capture surges as it is cheaper to replace than my EMS, but the EMS handles not only surges but low voltage issues also.
Here is what I use for my 30A RV:
30 AMP: Progressive Industries 30A Electrical Management System: https://amzn.to/3dFDnvx
30 AMP: Surge Guard Surge Protector (30A): https://amzn.to/3AbnSG7
If you have a 50 Amp RV:
50AMP: Progressive Industries 50A Electrical Management System(EMS): https://amzn.to/3gZiJZk
50AMP: Surge Guard, Surge Protector: https://amzn.to/3h1yG0Y