I would guess that his total "net worth" is more than that, but also take into account a lot of the net worth athletes have is conjecture. But also, the "big names" have their hands in many cookie jars. Endorsements, businesses, etc. Not saying that explains why his # is so low, I suspect it's because that # is outdated/inaccurate.
Why do I say that # is probably oudated/inaccurate?
The same website implies Damians net worth is 70 million. Considering Nate Jones stated that Damian kept his entire stipend his first year or two and invoices every dollar coming in and out, I don't think it's that low.