Lots more involved than just risk management. Like fear of losing, fear of missing out, fear of being wrong, not having a well thought out plan, not having the discipline to follow your plan. Lot of things but certainly not just risk management. .
I guess my point is that there is no relevance in labeling one as a hobbyist, or pro, or whatever. What I would think is relevant is how well one can trade. A so-called successful hobbyist may be 'early' in their hobby--having just discovered/created their holy grail; and might actually be growing wealth at a rate sufficient enough to soon be able to change their 'label' to pro, with respect to US tax code--should they choose to, they could actually also be a 'better' trader than a/a-few/many/most pros with respect to non-institutional trading/algo-coding abilities. tl;dr What is in a name?
Well, words do matter. And unfortunately it is common to conflate "professional" with "expert" and "amateur" (aka hobbyist) with "novice". The truth is there are novice professionals, expert professionals, novice amateurs and expert amateurs. Pros get paid, amateurs don't. Got nothing to do with the level of expertise.
That's where a lot of rookies go wrong trying to understand prudent risk management. It's more than risk reward.
Prudent Risk Management is not only necessary, it is the crux of successful trading. It is the only thing that matters.