I really like buying things from gamblers, because they give very cheap prices far from the usual prices. I once bought a cellphone whose market price was around 500 USD, because I bought it from a gambler, I got a cheaper price, namely 300 USD. So I can save up to 200 USD, quite profitable isn't it. And it's not uncommon for me to buy goods from them to resell so that I can make a bigger profit than the price difference given by the gamblers.
Gambling addicts have very poor emotional control, which can lead them to make bad decisions. So when they sell goods, they will never think twice about selling goods at a cheap price, because the most important thing for them is to get some money so they can continue gambling. And they believe that if they continue gambling, they will get bigger profits, so they can recover the losses they experienced previously.
Selling off properties and being in debt just to gamble is one big gambling madness that I still don't understand why a gambler will make them an option. You are actually right, gamblers who sell off properties lack emotional control, this is why they only act on what their emotions tell them without considering what will happen if they don't win.
Someone made a post here earlier stating that overconfidence is one factor that makes gamblers do the unimaginable just to gamble. Yea, that is true because if not for overconfidence, what else will make a person sell off his properties with the hope of replacing them immediately?
Advice doesn't really work on most of these people, sometimes it is better to let them learn bitter lessons themselves, then, they will think twice next time when making any decision at all.