Not surprised! That's the beauty of cookies! We read, write, share, browse, and discuss topics related to domain names. Hence, relevant ads on unrelated websites! You/We have been identified as potential buyers of domain names.
Why six figures? Now, when you see a vegetarian tiger, it will definitely be discussed among tiger lovers! Similarly, now this topic has been raised by you and is being discussed by domainers and investors! Maybe as satire! But still, I think it reached exactly the targeted audience. They may even reduce their prices. You mentioned you were reading an article about fire ants, yet they tracked you down through their tracking technologies and showed you their ads. Well Done!