You can't. The only "possible" solution would be to cut the ways that hackers use to farm cash (which in real life would be a non-stop printing cash/assets). For example making the mobs to not drop meso bags anymore (real life is stopping the goverment or private banks from printing cash/assets).

But then that produces an obvious problem: the deflators in the game (NPCs, starring, taxes) will eventually produce a cash crisis where a market can't be held for lack of cash, and people would resort to trading items with items. Now we can remove those deflators, but then you have effectively an economy without movement: no significant cash inflow or outflow means the economy can't reshape its size effectively, which producs a massive market volatibility which sometimes kills savers and sometimes they are blessed with unfair benefits. So a constant inflow and constant outflow must be retained for a healthy market.

But then, no matter what kind of inflow you introduce, botters will abuse it 24 hours, 7 days a week, giving them a massive income gap. You can reduce the meso cap to for example 100mil, reducing the gap between the legit inflow and botting inflow, but then people wouldn't be able to trade effectively high value goods (in fact, people already struggles to trade with mesos for some goods). You can also, like China Maple does, make the game give 0 EXP and 0 mesos after 4 hours of playtime a day so botters inflow are limited, but that would be a highly unpopular measure which would angry the dedicated players or anybody who wanna spends a lot of time in a given day, Chinese Maplers already resents it a lot, our dying GMS might not even be able to survive such measure.

In real life, what stops hyper inflation are a change on goverment policy, which usually means the same goverment (or like usually happens, a coup or change of leader, then a new goverment) stops printing cash like retarded, or stops the banks from spamming assets like retarded. Sadly, Maple Goverment can't stop banks from spamming assets like retarded, AKA, the botters, since they are unwilling to properly ban them, thus making hyperinflation unavoidable.