Bots give the player an instant advantage.

Sure you could spend 6hrs a day for 2 weeks to make that 20million to buy that +3 endgame piece you want. Or you can go to work have a bot go for you and come home and play the game how you want to instead of farming.

Is it right.. NO, but it is why people do it. The bad thing is it seems the bot devs are always 1 step ahead of SE on detection, so there is not a way to really stop them since they need "Proof" they are botting.