That's why I chose to learn reading. For me, reading was easier than speaking.
It's very difficult to understand locals because of the many accents and dialects. So, once I started reading and understood the tone system and basic grammar, I started speaking. I didn't learn much, just a few months (about 3-4), and that was enough. But now it's really helpful when I need to say something and don't know how—I just read the word and know exactly how to pronounce it. Or when I'm traveling, reading is the best support, because Central Thai is used everywhere in Thailand for writing, and you can easily read signs or information you need.
Of course, to reach a normal level, you need to study and study hard at school or university, but you can also pick up some basics on your own, fortunately, there are plenty of resources online.
In my case, when I arrived in Thailand, I didn't know any language other than my native language, so I had to learn English from scratch. Now I spend more time learning English than Thai.
RE: You don't really need to speak the local language to live in Thailand