I think because they like easy ways to do things,put your money and wait for profit,but in bitcoin you have to learn and read first about it,because it's not a simple thing for ordinary men,so that's why ppl doesn't see the difference between ponzi shceme and the right way to invest in cryptos.On the other hand, people who think they have limited time may make calculated investments and not worry too much about losing,or making a small profit.