I grew up with hardasses. Some of them had earned their hardass badge--the depression, poverty, etc. But they weren't a lot of fun to be around.
It's not always a blue-collar condition. I've seen it in corporate CEOs and academics. The CEO whose management style is a skillful wielding of contempt. The academic who scorns emotions. In academia it's not confined to the male gender. It's sometimes used as a preemptive strike, e.g.; sarcasm directed at someone who doesn't agree with the tenets of the little patch of turf they've staked out.
I'm sure it's about fear. I've got so good at spotting it I know how to get a reaction. All you have to do is ask them something personal and watch the shields go up. I want to know what they're protecting. I want to see inside them to the little kid sitting there in the dark.