Aaron Davis’ wife thought it was absurd when he spent $312,000 on a one-of-a-kind LeBron James trading card in 2016. That assessment has not been officially retracted, but only five years later the card could fetch well over 10 times that at auction, experts say.

In July, another James card — this one not nearly as rare — sold for $1.8 million. That caught Davis’ attention because there are only two versions of that particular card that share the same high quality, and Davis, a 42-year-old investment manager in California, owns the other one.

Davis keeps those two cards, with a combined worth in excess of $7 million, safely squirreled away in a bank vault with some of his other prized specimens.