Most of the people I know have sometimes in their lives borrowed money to some Thai person and never got it back. But it is not only foreigners that lost money to Thai people, Thai do not pay back to Thai as well. Most people say in Thailand that if you borrow money to a Thai person it is the same as a gift. Thai people are terrible with money and if they have any they are like fire in their pockets they need to spend it.
Last week a temple in Thailand put up a sign in the temple saying that they did not want anybody to come to the temple and borrow money anymore. People have been coming every month to borrow money for rent and food but just spent the money on drinking and gambling. Now the temple is running out of cash and told people to pay back what they borrowed.
You might feel sorry for all this landless farmers in Thailand and yes some of them are really landless and have a great misfortune happened to them but many of them just sold the land to get rich quick and after that the just spend the money on drinking other things. When the money is gone they go complain that someone tricked them out of the land and they demand to get it debt.
Thai people also have mafia lenders that borrow money to everyone that wants to. They charge a terrible interest and most people can never pay back but pay the loan shark for the rest of their lives. But so many people in Thailand live outside the system and cannot borrow money from normal banks that these loan sharks play a role in Thailand. The terrible thing is that people also borrow money for buying luxury items and some even gamble with the money, putting them and their families in just greater in debt.
This debt problem has spiraled out of control with the introduction of credit cards a few years back when everybody could get a credit card with 100 000 THB credit. Many Thai just took out the credit card to max and never paid back any money to the banks leaving them outside the normal credit system for life. If they could not take out cash they just bought a TV for the money and then went to pawn shop and sold the TV to get cash, they made a huge loss but they got cash quick.
If you are a foreigner and a Thai person want to borrow your money or invest it for you just think it as gift. Do not expect to get it back because you normally never will.