Why it is difficult to learn mathematics

One more citation from Peter Woit, 2006, Not Even Wrong, The failure of String Theory and the Search for Unity in Physical Law (Chapter On Beauty and Difficulty, p. 201)

 Mathematicians don’t make things any easier, since readable expository material about much of modern mathematics is sorely lacking. The culture of mathematics values highly precision, rigor, and abstraction, not the sort of imprecise motivational material and carefully worked out examples that make a subject accessible to someone from the outside trying to get some idea of what is going on. This makes the research literature often impenetrable to all but those already expert in a field. There is often a somewhat intellectually macho attitude among some mathematicians, an attitude that since they overcome great hurdles to understand something, there’s no reason to make it easier and encourage others less talented and dedicated than themselves.