Firstly, when people genuinely realize that something is really important but keep on regretting that "I am too busy hence I cannot learn something or do something". I hear it as if they are saying "I am hit by the procrastination bug".
Secondly, when some others say that "I am too busy, so cannot do it" I hear it as "That's not my priority"
A classic example from my personal experience was that I badly wanted to visit the dentist for about three months, but kept on blaming it on being busy and couldn't find time to go. Then one day in the middle of the night I got a toothache and all of a sudden I am no longer busy and the first thing in the morning I am seated on the dentist's chair! Now suddenly I got all the time in the world to do this and then attend to the other work!