It's amazing what people can be conned into. In a fraud case I was involved in (translating, not defrauding, that is) there were several victims who had invested in an online crypto trading platform. Their account pages showed their initial 2000 or whatever had increased to 40-50,000 within a month or so. As it would...

When they tried to withdraw their 'profits', they were told they had to pay tax upfront - about 4,000. They paid the money, then got a message saying there had been a problem with the transaction, and they would have to repeat the transfer. Which they also did.

It was only when the third demand for a further withdrawal fee for another few thousand came in that 'at this point I began to become suspicious'...