Any money that was made via alt farming (back when it was possible) and bots, is illegitimate money, and make no mistake, a lot of people have used bots as well, and still do. It was gained by abusing a glitch or unintended part of the game. And what I mean with the addition of buying in-game money isn't that it's inflation cause it was added, it's inflation cause if you compare the price of a certificate, with how much it would cost if you bought in-game money, you will see a very huge leap. The inflation is not something the devs created, nor does their prices reflect that to the same extent (perhaps only in 2 bedroom), but it can be seen in the economy that players have created.
Edit: Whether or not the inflation is an issue, I don't know. I feel like it is, but that's just my opinion.
Edit: Whether or not the inflation is an issue, I don't know. I feel like it is, but that's just my opinion.