Sort:  

They take advantage of people's lack of knowledge and always look for the most economically vulnerable population, those who need to risk a little bit to get lucky and win or those who bet what bit they have out of necessity.

That's what scammers do, to take advantage of those who lack knowledge because they are often the ones who fall for it. Some win, most lose.

My grandparents had a saying that thieves or swindlers always want to do what they can to poor people. In this case with people with bit knowledge and money.

Yeah, your grandparents are right. Swindlers usually target the vulnerable people.