Often people make us cross, for some reason or other. It's when we don't attend classes, meetings or whatever... we are the one's who lose out... Not the ones who offended us!! They carry on and continue to learn things and somewhere down the line, do better and go further in life than us!
So we can be our own worst enemy!
So it's up to us to gather info all the time, because you never know when you'll need it. And in the process you're learning and growing more effective in whatever you're doing in life.