of course if you have a visa, however you can can only enter the country so many time depending on the type of visa.
Without a visa, you need a return flight. You can’t enter any country without a visa or outbound ticket. It’s like what’s happening at the US border, migrants are just trying to enter the country illegally.
Bottom line is don’t try and beat the system. Because one officer was lenient doesn’t mean the other will. They can easily ban you from entering their country if you don’t follow their laws.
Then when you try to leave you will get fined and may never be able to return to Thailand again. Everything is linked to your passport when you check in at your original flight and upon arrival at immigration no matter what country you travel. If youve been doing it and haven’t been caught you’re lucky eventually you will get caught. You can’t beat the system.
Im sure you need a confirmed outbound ticket for international travel if you don’t have a visa even if you travel non-rev. however, you should be able to buy a confirmed ticket at a discount rate using your retiree status. Visitors cannot roam the country freely as long as they want without a visa.