>> Guys, if I buy a photo camera

If you buy one camera, you are likely a billion times more likely to buy another. And, you have the disposable income to be in the market.

>> there's things one doesn't buy again often, like washing machines

You are not a whale, but you might be. Most people only buy one washing machine but a few people buy dozens (apartment managers and such). Such people, whales, sometimes buy one as test case. So ya, if you buy one then you are a strong maybe for one day buying many more.

Sometimes I wonder if it's about returns. "You bought one washing machine, but you might not like it and return it, so how about these others". Could even be that they're tracking sales only rather than sales minus returns, because returns take longer to come in so the metrics are harder to track.