Caveat: Art is in the eye of the beholder, it's all subjective.
However, this particular beholder doesn't get this one being worth $4mil.
If I had taken it, I'd be proud of it for sure. Good balance, very nice composition. The clouds even cooperated by being parallel for him. Technically competent. I'd even post it to CR as one of my fave landscapes.
However, I could go to the same place and take a picture 98% as good on any given cloudy day. I don't have an 8x10 camera, so I couldn't print it as nicely large, but is that what comprises art?
It's not about gear IMO. It's about technique, patience, scouting and oftentimes, luck. I think alot of "art appreciation" is taking something from a famous artist and justifying it. That's why so much famous art really is stuff that could be seemingly reproduced by almost anyone. Most people not trying to justify a piece's fame are taking it at face value. It's pretty easy to spot a critic desperately trying to back into a complement for schlock a famous artist is throwing out there b/c his boat needs to be refinished or his wife wants a new kitchen.
I think that any picture expensive should be a once in a lifetime event, beautifully captured by a photographer that knew exactly how to capture it. Those usually get Pulitzers, though, not $4mil
If I had the money, I'd pay for the one and only print of Vietnam/napalm girl, or Lee Harvey Oswald being shot. That photo of the Hindenburg.