Because they think this is the best way to make money, they think they can use words and earn a lot of money without putting their labor to create it.
in my opinion people scam because they desperate to have an easy money from the other hard work
People scam because they badly need money in an instant and easy way. They scam because they do not want to work to earn for what they need and what they want in life, they just want to commit bad just to provide their vices in life without thinking the welfare of the victims. Scam is very common nowadays, and its hard to eliminate them so we have to be wise enough not to talk people whom we really don't know at all.
I think OP is not really into scamming and how people do it, but why people are not giving money to those who are begging or asking money. it is simply because it's hard to earn money and if you would just give it away, well, sooner or later you will be the one who is begging for money.
we should always take a look at those who are asking for money, if it is begging, then look if they are really week and incapable of working or if they are doing it for a certain reason.