Ask HN: Looking back, what have you wasted lots of time on?
Math.<p>They tell you it&#x27;s useful (it is) and beautiful (in a way, for a slightly stretched definition of beauty).  What they don&#x27;t tell you right away is that there&#x27;s no end to the stuff.  Sooner or later you have to say &quot;enough.&quot;  And since a significant fraction of what I learned before I said that was useless [1], I wish I had said it sooner.<p>[1] I know you&#x27;re not supposed to say math is useless.  It&#x27;s the kind of thing a disaffected sixth grader would do.  But there are a lot of unnecessary proofs in math: things that seem perfectly obvious and are in fact true, but that require a long and counterintuitive argument to prove.  Time and again I read the argument, pondered it, more than half-memorized it when the books could just as easily have said &quot;A complex argument is necessary to establish what is obviously the case.  Find it if you want to in Appendix J.&quot;