Used Nikon D800 - Good Idea?

I'm looking to buy a new camera in the somewhat near future and I've decided to stick with Nikon DSLRs. I was thinking of getting a refurbished D7500 for $600 from B&H, but I started looking at used cameras... Uh so, a used D800 isn't actually much more than that. At KEH, for example, you can get an excellent example for under $700 (with the 10% discount). That's a lot of camera for the money. Of course, it's a lot higher resolution than the D7500. A larger viewfinder (which is one of my favorite parts of 35mm film cameras) and other advantages of full frame. Of course, lenses cost and weigh more, though there are still a lot of affordable lenses, and a lot of the ones I want for DX are FX lenses (FX ultrawides are significantly more, however). Lastly, there is the weight... I come from a D3300, so a D800 is literally double the weight and still considerably heavier than a D7500. But come on... it's full-frame! All joking aside, there's a pretty interesting debate going on between my heart and my brain. I'll definitely have to check out some FX cameras. I held a D850 and was practically smitten, actually.

For reference, I do a lot of mixed shooting, though I mainly enjoy landscape and wildlife photography. The D800 seems to be better for the former, though the d7500 may be better for wildlife photography because of the higher frame rate, though that hasn't been much of an issue on my D3300 (autofocus and tracking are bigger issues). The crop sensor also gives more reach and has a greater pixel density, so maybe it'll be better. Video, while nice on the D7500, is not really a deciding factor.

As a side note, there are surprisingly few used D800s (guess no one wants to get rid of them ).

Weight is still not in the equation, it is all a matter of
DR and iQ. In this, the D800E served me very well and
specially in wildlife applications.

I'm definitely considering it.

I still use a D800, you will NOT do better for that 700 bucks! You'll need good glass for that 36+ MPs to shine though, keep that in mind.
Mine's not for sale, btw.

I've actually decided to up my budget and go mirrorless after spending a week with a Sony a6500. I really don't think I would like a huge camera like a D800, especially not with the bigger, heavier glass (also significantly more expensive). I'm saving up for a Fuji XT-3 because I've decided that I don't really need full-frame, and the Fuji has excellent AF and an excellent burst rate for wildlife. There's a good assortment of lenses too, and new adapters seem to be very promising, even with telephoto lenses (like the Sigma 100-400). It also just seems like a great all-rounder; something I could use for anything and wouldn't take up too much space or weight.

Yes, Using Nikon D800 is a good idea. It is well known for its features and quality.