You spend your company's money on private immoral fun of customers, customers spend their company's money on your products/services instead of the otherwise not so different competition. The key part is that nobody actually invests their private money, but the value they get out of it is private. That's why it works and that's why it's usually illegal, and like most illegal things it happens anyway until someone at the top gets really pissed with you/your department/your company specifically.