Not to be unhelpful but no one can really answer this for you because it comes down to you, your interests, and what you spend. It can range from <$1000 - $10k / month - all are possible in Thailand. Just come and track every expense you have for 1-3 months and you will get a good idea after that. In Bangkok, I spent no more than 100,000 Baht / month. Average would be 75k baht.
erm interesting logic there lol. I just find it interesting that they complain about so called nomads sitting quietly in a coffee shop working on their computers and say it’s not real work. It shows a lack of understanding and awareness
90 day reporting is under immigration. Your visa is issued by the consulate. They don’t need to tell you the law. It’s up to you to find out the law. It’s required if you stay more than 90 days
Of course I am in Thailand but I don't ever spend anytime in Starbucks. Obviously it was tongue in cheek, of course people go to Starbucks. Maybe try a real coffee shop tucked away out of the tourist scene with local coffee and locally owned, not a franchise. There are too many in bkk. We just have different experiences I guess.