These giveaway scams are so lucrative due to the right-end of the tail of the handful of victims who lose a lot. This is called the whale model, compared to typical email spam, e.g. pharma, where there is less variance and smaller but more numerous payouts . The whale payouts are so much bigger than the others even combined, so much more profitable.

Also, it scales much better due to the popularity of crypto and irreversible payouts, compared to pills ,which are heavily regulated and have lower profit margins (due to shipments, SEO, and creating a storefront) and payment problems. This can explain the enduring popularity of giveaway scams despite efforts to stop it.