it'd be in terms and conditions that every MMO makes you sign before even launch the game. not to mention if you went for the lawsuit anyways, they'd countersuit for lost time and defamation to game image.
When you call the bank for a charge back you'll notice it takes 2 weeks to come back. This is because they do an investigation themselves. When they see you "gambled" money to get higher stats, they'll either:
• Decline on account of gambling (you get what you pay for)
• Accept on account of customer service (restrict future purchases ie never let you purchase at gaming companies, rental places, anywhere you could basically "want your money back because you weren't satisfied with your purchase")
Then because you filed for it, gaming company will receive a notice and blacklist your card, then report it within their organization who may also blacklist it
• Grand Theft auto IV
… • Grand theft Auto Franchise
…… • Bethesda
……… • Console Marketplaces (XBOX Marketplace, STEAM, ect)