What is the ruling on multi-level marketing, and where is the impermissibility or usury if the company requires the marketer to purchase its products in order to join, knowing that this is considered one of the most powerful modern marketing methods, and that the marketer's money is paid in exchange for real and valuable products?

Multi-level marketing that requires a direct or indirect commission (through purchasing an overpriced product) is impermissible, as it falls under gambling. This is because it is based on either profit or loss, and the majority of participants incur losses. However, if this prohibited aspect is removed and deception is avoided, then it may be permissible.