Long-term visas for non Thais, but you wont qualify
This is kind of an ongoing joke in Thailand and it rears its ugly head every now and then. Once in a blue moon some clueless and out-of-touch-with-the-common-man bureaucrat will come along with a solution on how to boost the economy by allowing certain types of people into the country. This is always touted as being an ideal situation that will benefit all of Thailand and all Thai people but then when you dig into the details of the proposed action you realize that this actually isn't going to apply to very many people at all or if it does, it will only apply to the ultra-wealthy who wouldn't really have a problem obtaining a long-term visa anyway.
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I want to take you back in time about 15 years. Virtually anyone could come into the country of Thailand and stay for basically as long as they wanted. Sure there were certain figurative bridges to cross and the usual red-tape or inconvenience of going on a visa run even though nothing actually changed about your status, it was just there to force people to leave once every 30 days or 3 months or however long your visa qualified you for. As long as Interpol and the FBI weren't looking for you, you could stay in Thailand for as long as you wanted to. Business was booming for literally everyone. Small, medium, and large tourism oriented businesses were making money hand over fist and Thailand was one of the most popular countries in the world for tourism.
Then the government, for reasons that I will never understand, decided to fiddle with immigration law over and over and over. Through bizarre legislation they enacted that you were only allowed to be in the Kingdom for 6 months out of every year and this resulted in long lines and immigration officials manually checked your passport for stamps and added up the number of days that you had been in the country. This caused massive delays and it was eventually scrapped. Then they changed the land crossing stamp to be only 15 days regardless of what kind of visa you had, this caused huge problems with people that were entitled to longer visas than that and this was quickly scrapped. Then they just left it up to the individual immigration officer to decide based on just anything, even what you were wearing on whether or not to allow you to have a stamp to come into the country. There are many more examples but the list basically goes on and on.
Immigration law changes so quickly in Thailand that even the agencies that specialize in this sort of thing don't have answers to your questions and neither do the people employed at overseas consulates. Online forums were filled with information about which embassy was "easiest" and which were "ball breakers" when in the grand scheme of things shouldn't all consulates be enforcing the same rules using the same criteria? Bribes were common and of course, if you had money to put under the table, ANYONE can get a stamp. There is no uniformity. Work permits are incredibly complicated and you will sometimes find yourself in a Catch-22 situation where you need a specific document from the Labor Department in order to qualify for a document from Immigration but you also need this same document in reverse thereby making it impossible for you to obtain either.
Chiang Mai, which is where I currently call home used to be the number one digital nomad residential destination in the world. Once they started fiddling with the visa rules we saw a mass exodus of this very large and relatively affluent portion of the population of Chiang Mai, there was at one point an estimated 60,000 digital nomads living and working in Chiang Mai for overseas companies. 60,000 people that were renting condos or houses, buying things at all manner of businesses, and as a consequence contributing greatly to overall tax revenue. A very large portion of these people have left the country and will be unlikely to ever return.
These days, if you look at any real estate group that focuses on property rentals online, you will see that there are now tens of thousands of condos that are available for rent all over the city and no one is going to rent them because the potential customers were chased out of the country.
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The community complained to the government so eventually some out of touch bureaucrat once again unveiled a "smart visa" that would allow digital nomads to stay in Thailand for up to 4 years without a work permit. There was just one very minor catch: You had to be making something ludicrous like 150,000 USD a year to qualify. I'm not an expert on digital nomadtry, but I would be willing to bet that there are almost NO digital nomads that make anywhere near that much money and if they did, they wouldn't be trying to live in Thailand. Also, most digital nomads are private contractors for multiple clients and it's not like there is a standard pay scheme for that.
Since this program was introduced 3 years ago, only a couple hundred people have applied for this visa and I would be willing to bet that most of them were rejected.
Those of us that are still here have our ways of getting visas but for the most part we are skirting the system by getting volunteer visas and then never actually volunteering or we will get education visas for a school that we never attend. The government routinely cracks down on these schemes and it just goes to show how out of touch the government really is. We wouldn't be skirting the system if you just stopped fiddling with the system. Everything was fine years ago but now it is just a mess.
It just blows my mind that the government is complaining that their tax revenue is down a lot because of Covid yet they have made zero adjustments to their visa policies that resulted in what is bound to be vast sums of money in tax leaving the country never to return.
I have a solution for a lot of your income woes.... get out of the way. There is an old saying that goes something like this "if it isn't broken the government will fix it until it is." This is exactly what the Thai government has accomplished as far as foreign residents are concerned.