I'm sure if the boss gets to find out the employees gambling habits and realise that he is addicted to gambling, even if the boss used to trust is boy their will be this strange feeling the boss will have concerning his money , if the money is in safer hand.
My Boss would not trust anyone who would gamble or drink or do drugs, not at all.
For him - the clear mind gives clear direction - and an addicted gambler would be crazy for money. So YES! It is a cause of concern for our office if a person is gamblor he would not be in our office.
I've never managed other people's money in my day job, but I've always had a rule not to spread the word in business circles and preferred to let only my close friends know that I like to gamble. I am not ashamed of my hobby as I have perfect control over myself while playing and do not spend more money than I had planned initially, but I think that gambling should not be told to everyone in a row.