I'm a believer now, it took a while for me to come around, but I have 2 different surge protectors. One is for 30 amp power, the other is for 50 amp power. I use the 30 amp on my 50 amp camper when there is no 50 amp available. It provided protection, at least enough to keep the power off if the receptacle is miss-wired. It has saved our keesters more than once with miss-wired receptacles.
OK, I had to argue with the campground management the last time, but they did send someone out and ended up swapping out the entire plug, the breaker, and wired it correct. No issues after that.
The power management or surge protectors are a good $200 or $300 investment to protect a $74,000 RV!