World of Warcraft. There's a lot to do there. I wish I could get back my wasted time 
To Re-Waste it.
Botting wow seems to me a precursor to mining. A ton of folks over at mmoglider made a killing in their heyday.
The problem with botting is that they ban your accounts. Blizzard is quite stupid doing that, as botters are also customers (which usually have multiple accounts and therefore pay more for games/expansions and subscriptions) and produce something very useful for other customers.
Although, honestly, you'd have to be blind to ignore how they assisted botters.The recruit a friend system awarded 1.5x the normal experience when in the same party and allowed a character to 'grant' 60 levels to a new player per level gained blah blah, whatever.
Not to mention they implemented this system after a banwave: odd how these were only periodic and the blizz devs would allegedly 'square off' with the mmoglider ones. You could get 3x level 60's in probably 1/3 time it would normally take to create all of these characters.
Who cares? Leveling in wow was enjoyable perhaps 1 time, and questing in new expansions is decent: but nobody would want to play through everything all again for each class. With warlords of draenor offering a free max level character it's hilarious to consider how many transformations this absurd leveling system has gone through.
At one point though people were selling near-itemless level 70's/80's for $200-300 and maybe $100/50k gold or something. Not bad when earning 20k gold/day excluding auction house arbitrage.
They have implemented some ways to facilitate levelling, but that doesn't matter much if they just ban your accounts, even before you have sold any gold. And also gold is worth much less nowadays.