Multiple stories here.
Gambling: If you can stand it, read the book "Born to Lose," by Bill Lee. His father was lost in a bet, and he, as a child, began gambling heavily. It's so well written, and really lays out how horrible this disease is.
Drugs & Alcohol: A cousin of mine is a big drinker and pot smoker. She has a good job and has been working in her field for about 15 years, but is completely dependent on her mother. She lives in her home, and has nothing saved. Being inebriated leads to losing money (lost wallet, etc.), hanging out with people who she "helps," and other things of that sort.
Alcohol: I have a very good friend who drinks every day. He makes good money, but is renting a condo when he'd rather buy a house. I began to really understand his situation when he and his wife treated my wife and I to a wine tour. We had so much fun. My wife and both got drunk, and were cut off, which is apparently "just not done" at those sorts of places, and it was a great memory that brought us closer to these friends. They even bought us 2 bottles of wine to take home, which, while great on site, seemed not so impressive when at home.
Later on, I found that they subscribe to a very expensive wine club, and also a cigar club, and whenever they go out it's never without a big drink bill. I have to admit, this was all foreign to me. My wife and I almost always order water at a restaurant.
[size=14ptTHE BIG COST FOR THESE FRIENDS[/size] is that they both want to have a child, but don't want to stop drinking. I have never seen them drink to excess, but to not drink at all just seems unbearable to them.