What's causing all the inflation?

Fixed.

DMCA notices apply to copyright violations. Not exactly applicable to meso selling sites anyway. Besides they'll have multiple DNS registrations lined up to crank up new sites. Nexon needs to find out if and how mesos are being hacked and fix that. If they are as some ppl have claimed, it may already be too late.

My assumption is that this is a packet edit since it's unlikely that each and every mesos has a unique identifier. So when you pick up mesos the packet sent to nexon has the number of mesos in it. If you can change that value to the maximum droppable value of 50k and nexon doesn't compare the amount dropped to the amount picked up then you have an issue.

Considering how many mesos are in use, the back end database would have to use some guid value to ensure that each mesos is different. I can't see that happenening as that would cause all kinds of trouble. If I traded 100 million mesos from one account to another and each mesos had a guid, then the backed database would have to delete from one table (my inventory) and insert into another table (other inventory) 100 million rows.

I'm not familiar with what backend database nexon uses, but on one of my production SQL servers at work, 100 million deletes and 100 million more inserts are going take a good amount of time. (measured in minutes at least)

Considering that trades and picking up even 50k bags don't incur any delays in game, I'd say it's safe to assume mesos don't have unique values.

BTW, when a monster drops a weapon or scroll there's often a noticeable delay, especially on slower computers.

@Froznlite
I agree that legits shouldn't be buying mesos from these sites. However, as the cost get smaller and smaller, the temptation will get larger and larger.