How many are infesting and investing in the Kingdom
"Thailand is unique among Asian nations. Individually, the country brings in a sizeable influx of foreigners from more affluent nations through the informal Three I policy of impregnation-integration-investment. Here's how it works. The foreigner, usually male, Impregnates a Thai female, then wishes to Integrate himself into the laid back Thai living environment by Investing in a bar or restaurant." Doug Knell, Doug's Republic
Men, usually older ones, find it easy to score here. Indeed, you could be mentally retarded and be born without a nose and still be able to pass on your DNA in the Kingdom. The easier lifestyle encourages them to stay, and a bar/restaurant is the simplest way, they deem, to fund the laid back lifestyle. This was discussed in detail here.
The Three I segment forms a more sizeable group than it would in the majority of other nations, but not all foreigners living in the Kingdom are older males and impregnation pros. Some are entrepreneurs, others English teachers, others expats working for multinationals, and still others on retirement visas with spouses they met while still in their homelands.