Why does it stay in business? Because there is nothing wrong with a company that exploits the greed of individuals. Yes, some people are compelled due to desperate situations. But the solution here is raising the education level high enough to not succumb to their inner greed. The solution isn't reactively outlawing knives that cut more people than others.
Mental decline happens to everyone. Not necessarily to a severe level that would make one incapable of living independently, but enough to make them less sharp. You may be young enough to spot a scam from miles away, but your senses will most likely dull over time. In a couple of decades, you may be just as likely to be featured in a news piece about victims of a scam as the ones you are calling uneducated and greedy now.
But there is a certain cruelty in doing business by deceiving people, and where the remedy is ex post facto “raising your education level” to become less deceivable.
There's certainly plenty wrong with it; perhaps you meant to say it's not illegal.
It may seem intuitively obvious to you that there are not moral facts (it seemed intuitively obvious that the opposite was true to people even as recently as 150 years ago) but the debate is hardly settled by any intervening scientific or cultural or philosophical advancement.
I guess read J.L. Mackie's "Ethics" for an introduction to the subject.