Or I guess I could pay extra to get a squaretrade warranty.
An after-market warranty is only an insurance policy. A basic principle of insurance is to purchase it only for losses that you cannot reasonably cover yourself, such as if your house burned down with everything in it. Few could afford to replace their house and contents out of pocket but if you find a $500 purchase financially scary such that effecting repairs out of pocket could be an issue, you might consider a more modest purchase. If you like Denon, the D2K is very nice, too, and costs about half the D5K.
For whatever it's worth, Consumer Reports analyzed the after-market warranty products and concluded that they are almost never worth their high cost relative to the underlying product; they "kick in" only after the basic warranty expires (the period during which most electronics fail anyway, if they're ever going to fail during their useful life); and require use of selected repair services who may not be convenient to you plus, typically, deductibles.
Speaking only for myself, if all my audio gear totaled, say $100K+, I'd have my homeowner's insurance agent in with an estimator to add the gear to my homeowner's policy. I would not purchase insurance for an individual $500 item. It's (the insurance) too expensive, offers only add-on benefits (after the basic warranty expires), and I would only make the purchase if I could afford to replace it out of pocket.
Naturally, you're going to do what you feel makes the most sense for you but that's how I would handle it.