But what are you insuring against? In the Midwest, where I am guessing he lives...there isn't a ton of risk with an extended power outage.
I guess you could amortize it over the life of the loan, which will make the cost seem small. That is also how you make a speedboat seem cheap too though. I guess I don't know that I would compare it to insurance. You need homeowners' insurance because you don't have hundreds of thousands to rebuild if it burns down etc. There are plenty of alternatives compared to a whole home generator, some quite cheap. I am guessing the average person, at least in the midwest, would be lucky to run into 10 times the home generator made a huge difference (aka probably a good 3+ day power outage). Heck, many maybe half of that over a 30 year life of a generator (usually considered max life, could be less). So you pay a solid $1k per time it kicks in to save the fridge or the house from being 45 degrees? There are probably better ways to spend $8k or so at that point.
That is kinda why I say, you have to find value in the luxury of it. Where the typical power outage of 2 hours, 8 hours, maybe 24 hour power outage being avoided is a huge value to you.
Of course, a lot of it depends on where you live and the infrastructure. My first step, if I was pondering a whole home generator, is finding a neighbor that has lived in the neighborhood a long time. Are extended power outages often etc.? If he can't even recall a big power outage, that is probably a sign it isn't much of a concern in your area. If you live in a newer neighborhood and all the utilities are underground...a big generator is likely going to be quite a waste.