The biggest point you missed is that I am talking about non traditional schooling. Of course things are easier when you previously learned them. You're also missing that I'm talking about encouraging what someone already wants to learn. I didn't learn computer science until I was 24, but now I'm employed as a software engineer. I only needed my own internal motivation to study. There's no reason you couldn't be a mathematician later in life without previously having studied mathematics. It's just an excuse to think you couldn't do it without having been forced to earlier.