Don’t lend money to Thais here, you give. It’s a gift from a foreigner. It’s just the way it is here for most, not all.
If you want to lend money for a business, then get an attorney to put your name on the business, 49% before you give.
Thais usually use reputation and public shaming on social media to retrieve their funds, then retract the comments when paid. It works, I’ve seen it many times. Though sorry, this method will not work for foreigners.