There are between 700,000 to one million illegal casinos operating across Thailand. Between $21 Billion to $27 Billion (640 to 820 Billion Thai Baht) are illegally wagered through these dens each year, giving the houses up to $3 Billion (90 Billion Thai Baht) in profits.
In Bangkok, there are about 170 illegal gambling dens, with $6 Billion to $6.6 Billion (180 to 200 Billion Thai Baht) wagered through them. The houses earn a profit of $1.2 to $1.3 Billion a year (38 to 40 Billion Thai Baht), with $66 Million to $267 Million (2 to 8 Billion Thai Baht) paid off to the local police.
(More statistics about illegal betting.)
Source: “Academic urges legalisation of casinos,” Bangkok Post, August 30, 2011.