Longform profiles of superstar dealers such as Larry Gagosian or David Zwirner provide more insight into the psychology of those who catch the art collecting "bug". And how it can morph into irrational idee fixe territory. Such as Getty's obsession with the Roman Emperor Hadrian.
The Art-World Insider Who Went Too Far
https://www.newyorker.com/magazine/2016/02/08/the-bouvier-af...
And of course, you don't need to be a millionaire to start building your own collection. Just a keen eye, good taste, and love for making deals ;)
How To Start Collecting Art In Your 20s
https://www.artsy.net/article/artsy-editorial-start-collecti...
The latest innovation and natural evolution of digital art collecting is potentially the blockchain and distributed ledgers.
The Blockchain Art Market Is Here
https://www.artnome.com/news/2017/12/22/the-blockchain-art-m...