This makes sense when you consider that it’s not Amazon paying for you to see those ads. Amazon is getting paid, comparatively, big bucks for you to be served those ads by them, because Amazon put your account in the “Searched for a GPU within the past X days” list, where your data can be sold to GPU manufacturers and board partners for more money than the people in the “Generally wants to buy something” list that you would be in, had you not searched for GPU’s extensively.

Amazon could totally remove your user from the GPU list after they detected that you have purchased one, that would make sense from a UX perspective to stop seeing ads for something you just bought but Amazon wouldn’t be able to make more money off you if they did. The GPU partners and manufacturers do not know you bought a GPU. Amazon is the only one that knows, and it’s in their interest to keep quiet so they can milk them for more money.

As long as your account has searched for GPU’s within a certain time period, you will receive GPU ads regardless of how many GPU’s you actually buy. You could buy Amazon’s entire stock of GPU’s from every manufacturer, and you would still be served GPU ads.