because people want to produce without doing anything, it has become a natural phenomenon, where you only spend a little money to multiply it, let's say 1 person sends 100 $ if 100 people then it becomes 10000 $, they are interested in big profits.
Smart scammers also use other possible versions of scamming people. Instead of scamming 100 people for $100, they prefer to make a trap for the whales at $10000. Greedy investors also fall to this trap usually, some people simply have no analytical thinking. Stay away from the advertisements looks too good to be true.