Much has been written here and elsewhere on the subject and I suggest you use SEARCH to find and read about it. Or this article may help:
https://www.escapees.com/rv-insurance-vs-rv-extended-warranty-do-you-need-both/
I'll summarize:
1. It's an insurance policy, not a warranty. BIG difference! It covers the repair of mechanical breakdowns (not wear & tear) of moving parts and some electronics.
2. There are many, many things not covered, e.g. the RV body, furnishings, and cabinetry, and many exceptions and loopholes for components that are covered. Don't take the salesman's glowing promises at face value - read the contract details carefully!!!
3. No DIY repairs - professional RV shops only. All repairs must be pre-authorized by the claims adjuster (usually by phone but sometimes requiring onsite inspection).
4. It's a huge profit maker for the dealer, so [if you decide to get one], either negotiate the price or buy from an agency/broker such as wholesalewarranties.com. The savings are likely to be substantial.
You need to make your own call on the advisability of buying insurance for repair costs, but my personal opinion is that there are not enough high dollar, failure-prone, covered components on a trailer to make it worthwhile. The sales guy probably tried to scare you with refrigerator and a/c replacement costs (and they are large), but you also need to consider the frequency at which such things fail in the first 4-5 years of RV ownership. And remember, the first year has a real manufacturer's warranty covering it regardless. An additional $3400 would buy you a lot of repairs.