It would certainly explain a lot:
We already know haters are predisposed to be that way. Now we see they also spend a lot of time at fewer activities than their non-hater counterparts.
But in a twist of irony, that grumpy person at work may actually be pretty good at their job since they spend so much time on fewer activities, thereby giving them the opportunity to hone their skills in specific tasks.
[…]
In two studies, participants reported all of their activities over a one-week period and also completed a measure of dispositional attitudes. Although haters (someone with a low dispositional attitude) and likers (someone with a high dispositional attitude) did not differ in the types of activities they pursued, haters tended to do fewer activities throughout the week than did likers. Nearly 15 percent of the differences in how many activities people conducted during a typical week was associated with being a hater versus a liker.
So, it's not that ham radio makes one grumpy, it's that grumpy people are attracted to ham radio.
Full text here.