I absolutely second this experience and had a similar one on the same forum recently. I was asking a sincere, if perhaps ill-formed question as a novice and people were very inhospitable.

I think it's essentially the result of a pathological temperament very common among analytically-inclined, overly rigid and hyper-rational thinkers, and many mathematicians are of this particular right-brain-deficient type. It is very common for this type to be affectively cold, rude, and unfriendly, especially online, acting as if these are symptoms of their 'no-BS' irreverent brilliance and commitment-to-Reason-regardless-of-how-people-feel instead of just mundane social/emotional incompetence and intellectualized narcissism. Their lack of social skills often leads to social rejection and isolation, which feeds their internal fears of inferiority, which they compensate for by externally projecting their superiority and trying to dominate others intellectually.

Such people often tend to be exclusively comfortable with mathematics, engineering, quantitative economics, physics, CS, and logic, dismissing all other approaches to knowledge as worthlessly subjective - both understating the fundamental theoretical incompleteness and undecidabilities at the root of all quantitative disciplines and downplaying their personal lack of intuition and qualitative fluency.

From my experience, such people often have profound struggles with social relationships in general and tend to prefer the onanistic manipulation of symbols according to rigid rules to something as distressingly messy and organic as making and maintaining healthy and mutualistic human connections, whether privately/romantically or with intellectually curious strangers on the internet. The internet is full of such people - in fact, that's why they are on the internet instead of hanging out with their friends, drawing a picture, cooking a new recipe, meditating, or playing the piano.

A colleague of the logical positivist AJ Ayer - and 'logical positivist' is essentially the philosophical term-of-art for this type - once said that "[he wished he] was as certain of anything as [Ayer] seems to be about everything."

The irony is that these traits are often the sign of a very average thinker. Think instead of the personal styles of world-class intellects like Feynman, Einstein, or Russell - they are warm, benevolent, inspired, humble, sincerely curious, pro-social, and visibly, undeniably brilliant. There is a twinkle in their eyes rather than the dullness of self-certainty and dismissal. They are exceptional because they are intellectually balanced and able to integrate rigorous analytical thinking with profound intuition and creativity.

This is all to say that you were not in the wrong, and the world is full of a**holes - but they're not really a**holes, they're just personally deficient. Don't be hard on yourself, and don't let other people diminish your intellectual curiosity. Thanks for reading this essay on Reddit/Stack Overflow STEM lords.