They don't really think that much.. Because they have never bothered to actually find out what it is.
It just means that they are not interested in bitcoin..Probably they are not in front of their computer the whole day...Most of those who are working in real life day job, might not be interested in bitcoin as they are earning big enough..
I do not think so. Because Bitcoin can be more flexible to be a part-time or just for time pass also. I have seen many full-time job holders are very much interested and doing with the Bitcoin investment very keenly.