It's been more than 3 years since the military staged a coup and has been ruthlessly suppressing dissent using the lese majesty laws and other laws they enacted that make it illegal to protest against the government. Tourist arrivals just keep increasing to record levels[1]. Tourists don't care, at least not enough to choose a different destination.

[1]https://tradingeconomics.com/thailand/tourist-arrivals

The counter argument would be neighbouring Myanmar, which is remarkably underdeveloped for tourists by comparison despite comparable tourist potential (and oil money to invest in infrastructure) because its authoritarian government has historically been boycotted, whereas Thailand's series of mostly authoritarian governments interspersed with elections and coups have usually played the international relations game just well enough to avoid becoming a pariah state.

But it's quite difficult to find a tropical paradise destination with progressive liberal democratic government

You mean a "cheap" tropical paradise with a liberal democratic government. You could always head off to Hawaii if you can afford it, or if you are in Asia, Okinawa or Taiwan.

But for those of us on a more restricted budget, Thailand, Indonesia, and the Philippines provide a better value. Thailand has always pulled through in being worth it for me, especially when prices crash after a coup.

Thailand has a coup followed by democratic government followed by coup every 5-10 years for about the past 50 years, what's happening now is no different to what's happened before. You're right, tourists don't care because by and large the Thai people don't care, this is nothing out of the ordinary for them.

Pretty much everyone knows that Turkey is a full blown dictatorship and yet I still have friends who go there on holiday. There's no connection in their mind between spending money on holidays in Turkey and helping Erdogan in the long term.

It's at best doubtful that tanking a country's economy will make it less authoritarian and more open to foreign influence.