Unsure if I would class HK in the Top Five online gambling countries, but I would certainily class them in the top 5 gambling nations.
Last year I thought a law passed making it illegal to accept gamblers from HK and operate from there (it looks like the HK Jockey Club has the best monopoly in the house).
http://www.adlawbyrequest.com/international/JockeyClub72301.shtml
Why This Matters: Online gambling is booming in Hong Kong. Operators of Internet gaming emporiums around the world have netted billions in profits from Hong Kong residents over the last several years. If the Hong Kong Legislative Council passes the bills requested by the Jockey Club, it could diminish the market for unlicensed online bookmakers.