Ok, lets talk about wow. they pay how much, $50 for a leveled up account boost? $15 in subscription every month? lets say $70 in investment. and you have the possibility, albeit low, to get banned by blizzard. blizzard has a policy that avoids banning users if possible.
The bots here in bronze, they invested how much? $10? per account? and they can multi account even with the same IP? botting in here is way easier than wow.
This actually helps the economy. The bots in bronze will get less cards, no dec, only potions and credits, credits which they will use to rent/buy power from other users, raising the market prices.
The less appealing the returns are for the bots, the less bots we'll see..
How would you would have tried to solve the bot problem?