I guess thats because that man is simply closed minded. Although I have often hear same instances like that, but to put it in general, those kind of people are just afraid to change because they think they would still fall on their vices again later on. And as what I have often observed, those who fall for different vices are usually those who have no permanent jobs, as they have more time for their vices than to look for a stable source of income that will make them busy with and that will give them a good income.
It can be a vicious cycle, actually.
People do not get a job because their vices, since they do not have a job then focus on their vices. There can also be some kind of mental illness or affliction which makes things harder for them.
I generally try not to judge people in those situation because I do not actually know them or know why there are "trapped" in such life style.