When you live in Thailand, be aware that there are things that can go wrong, just the same as your own country.
I think the biggest issue is underestimating the cost and running out of money.
Year after year, costs across the board increase. If you are from a country where your pension is frozen, you may find out 10 years down the road it is not enough.
Costs will increase and if you plan on spending the rest of your life in Thailand, estimate what those costs might look like in 30 years.
Another thing that can go wrong is medical. No one stays healthy for ever. Sooner or later you will get walloped with a gigantic medical bill. Insurance may or may not cover it. If you had existing medical conditions before coming to Thailand and have no insurance, having enough savings to cover a huge medical bill is a must.
Relationships. Whether just having a girlfriend or a Thai wife, there is an extremely high rate of relationship failures in Thailand. If you are in a relationship it might be a good idea to have a plan what happens when it all goes south and how much it will cost you.
Slandering businesses or causing Thai’s to lose “Face”. Not only can you get arrested and get sued, you could put yourself in the path of physical danger.
Lack of Safety. Every year, people are killed in mini-van crashes, bus crashes, tour boats capsizing, zip lines breaking and others. Never assume Thailand is safe!
Getting arrested for any reason. It is simple. Do NOT break the law in Thailand. You will soon find out how extremely limited your rights and chances are.
VISA issues. It is paramount to keep a legal visa. Why risk it if you do not legally qualify to be here?
Death of your Thai Spouse. As a foreigner you cannot own land. If your Thai wife passes away, make sure you have the correct paper work in place prior so that you will not get ejected from your own land.
Starting a company or doing a job reserved for Thai people. It seems many foreigners are ignoring this currently. You will find out quite quickly how fast the locals will turn you into the police.
Things can go wrong in Thailand and you should always be aware that is the case. If you subconsciously remember this, you will be much better off year after year.