In a nutshell if you can't get what you want at the ballot box, it's the alternative. They hope that if enough turmoil is created in the capital city of Bangkok the military will step in, and set up a government more to their liking, preferably an undemocratic one. They've called for a government of appointed leaders and yet they call themselves the Democrat party.
Thailand’s oldest political party, the Democrat Party, last won an election in 1992; its conservative, pro-bureaucracy bases in Bangkok and the south are not big enough for it to secure a national majority. And this very sore loser is now playing a central role in trying to oust an elected government.
NYT OP ED by Maccaro
Opposing them is a political party begun by a charismatic billionaire named Thaksin has won elections in 2001, 2005, 2006 2007, and 2011. His opponents initiated a military coup in 06, and the Thai courts which are as non partisan as our own Supreme Court have twice outlawed his party and convicted him of corruption. He remains wildly popular and that doesn't sit well with the Bangkok elites.
Why is Thaksin and now his sister who is the sitting prime minister so popular?
Yingluk, Thailand's current PM and sister of Thaksin
Thailand like the USA has vast income and wealth inequality. More so than in most countries worldwide. Thaksin brought universal health care and reform and investment to the provinces via village development funds. His opponents call that vote buying, I'd call it doing what governments are supposed to do.
The divide isn't simply rich versus poor but rather rich and middle class urbanites on one side, and middle classes from the provinces and poor on the other. There are also geographic divides that one could draw lines with language for simplicity. The North East where they speak Lao, the North where they speak Thai Nua (similar to Lue) versus the Central Thais of Bangkok and the South where there is a years long bloody Muslim insurgency.
There are many more poor and middle class from the provinces than there are rich and middle class from Bangkok. The rich will always lose in the democratic process, and they know it.
Life under the bridge in Bangkok
The democratic populism of Thaksin and his followers also threatens the royalist power structure that has really ruled Thailand for time immemorial.
Verapat Pariyawong, a Harvard-trained lawyer and commentator, says the powerful bureaucracy and courtiers around the king fear that new elites, symbolized by the rise of Mr. Thaksin, will replace them.
The Crown Property Bureau is by far the largest landowner in Bangkok and has controlling stakes in some of the biggest companies in the country. The managers of this fortune are among those “acting behind the scenes,” Mr. Verapat said.
In Thailand, Standing Up for Less Democracy NYT by Thomas Fuller
Both of my linked articles will I hope bring clarity to anyone with an interest. Most people I know who are Thai, are wealthy and from Bangkok. They talk of ignorant provincials whose votes are easily purchased. They place great value on their US graduate degrees and their father's money. The other Thais I know, former prostitutes married to Americans, say nothing, they come from more poor circumstances.
Most of the media is out of Bangkok, and reflects that fact. The two major Thai English Language papers, The Nation and the Bangkok Post are more nuanced giving voice to alternative views. The US media is at first supportive of the protesters as they represent their contacts, wealthy English speaking Thais. Asia hands such as the current Asian correspondent for the NYT or the former correspondent now Op Ed writer Christof not so much. I'd recommend a read of both of my links. Al Jazeera has had probably some of the best coverage.
Everyone remembers the human rights abuses of Thaksin in his war on drugs. The extrajudicial killings by police in the provinces usually of minorities people, but Thaksin was elected, and his party has won many times, most recently by large margins in an election with participation that we could only dream of. In the end you have to respect the democratic process.
Apologies in advance for any misstatements of fact. If egregious I'll fix them. It's been twenty years now since I've last lived in Bangkok or Thailand and I don't follow issues very closely there.