One possibility is that they're gambling addicts in countries where gambling is heavily restricted, and buying "loot boxes" containing random items is the closest they can get to playing a casino slot machine.

Or perhaps they think of themselves as clever investors in collectables, which they hope to sell on at a profit later on. You and I might think they're buying the equivalent of tulips or beanie babies - but they think their purchases are more like fine wines or rare postage stamps.

Perhaps the big spenders actually only spend big five bucks at a time, and they're merely poor at managing their personal finances - spending five bucks a day for five years, unaware of how it's adding up.

Or it could be money laundering - perhaps there's some criminal scheme where bank transfers are heavily monitored by the cops, but transfers of rare TF2 hats aren't.

Perhaps the big money transactions are actually fake, aiming to pump up prices or make people spending mere hundreds of dollars feel better about it because at least they're not spending thousands.

Yet another option is that they're super-successful billionaires, and a thousand bucks is nothing to them, not even worth bending down to pick up if they saw it in the street.

People who make games with microtransactions for a living probably find it a lot easier to sleep at night if they think all their whales are billionaires.