Usually the ones who hide are the ones that are degenerate losers. Year in and year out I have a friend who gets stuck every year to the man. The funny thing is he believes he's going to win. His homework equates to reading the local paper's lines & standings then firing $50/100 plays on NFL Sunday ( yes there are squares out there not that I'm a sharp or anything) and when all said and done he'll be in the red. Try to point him in the right direction to cut down his loses and maybe win is a loss cause. Gamblers have big egos especially the ones that don't know jack shit about this business............what a gold mine.
I wouldn't go as far to say those who hide it are all the degenerate type. Seems like the guys that are always talking about it are the ones who have the real problem... parlaying and teasing left and right, always betting the sucker bet, etc...
Simply put, there's a stigma attached to gambling and gamblers in general because of the actions of those truly addicted to it. Are there those that can gamble and do so within their means? Certainly... But the ones most people see are those that are living paycheck to paycheck, throwing all of it on the big game.
I know personally that when my girlfriend of the time didn't think it was that big a deal that she mentioned to her father that I gambled on sports that I was extremely embarassed. Do I see a problem in it? No. But I'd go out on a limb and say that most people do.
The topic is hiding it from your better half not the public.........honestly is the best policy..............your MM skills may improve once she is in on it. Spending the diaper money............well we all know that's wrong. Trying to get even can get you even worse.
I took some good advice way back, that was to be upfront about (10% of) your gambling to those who really matter in your life. Those close to you will eventually find out, and probably not in the way you would like.