if we are reliable traders who are able to analyze well, then it is very good for full time trading. not all traders can afford to take the time to analyze the market, some of them are free fall to trade with immature skills. they are motivated by people who are successful in crypto. so sometimes they can't analyze well, due to lack of trading skills.
I myself take the time to do market research, and I can't leave my main job. because in case the market weakens at any time we must have other income.
Yes, not all times the market is strong but other times it is weak and what can a reliable trader do in this situation? nothing. That is why it is important that he have another source of income (like you said) but that income or job must be stable and reliable at all times.
Those traders that you saw that doesn't have enough time to monitor the market are may be busy on their main jobs but in trading, it is now possible for a bot to do your trades so there is no need for a real time monitoring. You should only check it sometimes if it still doing its job properly. It is okay to fail at first especially for beginners but eventually you will become better at it.