Maybe it also counts transactions from the Steam Market? I also found my TotalSpend hard to believe, but it’s also not like I’ve traded hundreds of dollars worth of items in the market.

The description of the support page notes that these values are used to determine some sort of limited user account status. It might not be intended to keep an accurate tally. I wouldn’t be surprised if these values are only available due to gdpr and accuracy of the description was not a priority when they set it up.

That or I’m huffing copium about my game expenses 😅