Your friend has two choices continue to be ripped off or educate himself.
There is a third alternative.
It's rather like I don't need to study for a medical degree - I pay someone else who has already done the studying to diagnose and treat me.
Similarly, when I need to get my car fixed I don't take a course in car mechanics. I take it to a reputable garage.
In the case of financial affairs, it's to take the advice of a qualified financial adviser, lawyer or accountant (depending on the particular area of finance concerned).
In the case of a doctor, I make sure he/she is qualified, registered with the medical authorities, and is working within a reputable hospital.
With the mechanic, I will use the local Toyota garage in the hope that the Toyota franchise, and Toyota behind them, will ensure quality service.
With a financial adviser, lawyer or accountant I would have few qualms about using an IFA (not a tied adviser), or UK-registered lawyer or accountant, or perhaps a fiduciary financial adviser in the USA.
Unfortunately, from Thailand it's difficult to access such quality advice, and people become victims of con men who give themselves fancy titles and work for companies with equally fancy names aimed at giving them a façade of respectability.
'Tis pity that the authorities here don't crack down on all the scam merchants preying on the vulnerable.