Perhaps, you have already answered your own question. When you are in Thailand, you get bored. Perhaps Thailand is not the place for you to retire.
Running a business, even if it is only with the goal of breaking even, is basically a 24 hour job. You could entrust it to someone else, but how does that address your boredom? It also dramatically increases the risk that the business will be run at a loss (perhaps great loss).
If you want to just have a place to hang out during the day, you can do that at gyms or cafes by buying a membership, not the whole business. But for that to work, you would probably need to be social, which you said that you struggle with.
Someone suggested learning Thai. Taking classes is a great way of scheduling your day, and you can learn a skill. You may not be able to volunteer in Thailand, but I would think that language exchange would not be considered volunteering. You could meet with local Thais in coffee shops and they can speak to you in Thai and in exchange, you can speak with them in English. A win win. It is also informal and could help you form social connections.
You say that you like to travel. You could just travel to Thailand regularly for periods that are short enough that you do not get bored and you can schedule many things to do during that time to keep yourself busy.
But honestly from a financial point of view for a person at a point in their life where they are “retiring”, I cannot think of a worse reason to start a business than boredom. The answer to boredom is not going to be found in taking on the risk and stress of running a business that your heart really isn’t even into. You might as well keep working in your current job.
