The problem is with the current drop rate (even doubled) in your whole life playing the game you aren't going to get 3 of them for the achievement. You can win the lotto 3 times? Yes, is not absolutely impossible (if impossible is the problematic word), but statistically in 100 years playing you are not gonna get it. This is not about getting a rare object, like the infusion, is about you need 3 extremely rare objects to get an achievement, and this is the first time Anet introduces an achievement like this. This is not like the 'I'm rich, you know' achiev, that was expensive, 1k gold, but anyone can get it. You only need the money and the merchant has infinite contracts to sell. This achievement can't be earned even being rich due the absurdly low quantity of these objects.