Statistically speaking, you're more likely to buy a second object right after you bought one than someone who has not shown interest in the product. Things break, you might want to return it for a slightly different version, you might buy one for a friend.

For you, it might be wrong, but when the advertiser is buying millions of ad impressions and is looking for a 0.01% hit rate, the math shows that you're one of the more likely future customers.