I agree that many people mistakenly consider trading as a hobby or casual activity. However, trading can be classified as self-employment because it is a serious job. The Big Indonesian Dictionary says that people who work for themselves are called entrepreneurs.
A trader is his own boss. Since the market is unpredictable and constantly changing, it is recommended that traders have a stable secondary income to support their finances. By having a stable secondary income, you can maintain financial stability and reduce the risks that may arise from trading.
Don't be influenced by other people's opinions. If you feel comfortable trading and making consistent profits, keep working towards becoming a professional trader. Learn and improve your skills.

What you say actually makes sense without having to refer to any big dictionary. Because in real life examples, it is quite clear that any trader would be better off if they had a stable secondary source of income in order to feel comfortable when trading for a long time on any stock exchange. So the option to have another source of income that can support the trading activities we are currently engaged in is a pretty good option if we can always focus on both of them on a daily basis.