Also, I don't know anywhere else on the internet that would be comparably good for asking such questions.
The reason for that is simple: anywhere where it's the norm to ask such questions is somewhere that research mathematicians aren't going to spend much time on! If someone not in the main academic stream is really interested in learning some mathematics "on the side" then they really ought to do the following: find a nearby university with a mathematics department, go there and ask to make an appointment with a mathematician - offer to pay for their time! - and ask them directly what they recommend. The mathematician will be able to give a much more focussed answer and so much more useful. Plus an initial contact will have been made which, if not abused, could be much more useful to the questioner. I would wonder at someone's understanding of what real mathematics is if they think that an answer to a general question on MO is really going to help them learn mathematics.
It's alright for someone who is already in the system to ask such a question, because all they really want is a "where do I start" - they have the support and network to continue. Of course, I would hope that they had asked in their own department first and I would hope that they had gotten the response, "I don't actually know about that area, but if you can find a place to start, then I'll be happy to help where I can.".
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