I was a cynical student myself. I flunked a few of my classes simply because I looked at them and decided they weren't useful or interesting to me. This was at a particularly anti-authoritarian point in my life (and I also wasn't that happy) so consisted of me just skipping the coursework and focusing on other intellectual domains that felt right to me.
Although I am sure this made me more creative (and doing things because I wanted to know more about the world has made me love learning), I was ignorant to not acknowledge the inherent risk in following your passions in learning. The world is stratified by easily measured educational standards - my string of As and Fs did not help me here, and when you are tested by somebody that is canon (and you will be) you will be at a strong disadvantage.
I had to fill in a few holes over the last few years. You can't always be sure that you won't need something, and even if you don't need it what if you are graded on it? It's crazy luck that my industry is fast-growing and was new and unregulated enough to accept me. If I wasn't in technology I almost certainly wouldn't have managed to come out of this unscathed.
Incomplete access to the mainstream educational signalling mechanism is a very dangerous situation. The other methods of signalling intelligence are a lot more difficult and have a much smaller market. (My achilles heel is institutional leverage, but my saving grace is being obsessed with learning.)
I couldn't have stopped myself from being who I was when I was younger. I hated being told what to do. I was too depressed to make myself do something that I wasn't enjoying (the first year of University was unfortunately an emotional ground zero for me and I rebuilt myself brick by painful brick.) But it's not right to say that specialisation and conforming is only important in academia. 80/20 rule is probably best for most people, maybe 60/40 if you're extremely secure...