So, if I'm working as a cleaning service, helper, and fruit picker, I only have to focus with my jobs and not looking for better opportunity? I'm sure as great as you work in these jobs, your life will not change, simply because there's no future with these jobs (didn't mean to discredit these jobs).
In order to improve your finance, you need to changes, however many people afraid or not want to change, that's why they stuck in the same place.
I mean changes are:
1. Blue collar jobs > white collar jobs
2. Saving > low risk investment > high risk investment
3. Playing game, clubbing, pleasing other people > learn new thing, have a healthy life, focus on yourself
There is nothing wrong with us being highly focused on our main job because any job, if we want to complete it, we need to be diligent and focused on it. But it would be wrong to say that we should only focus on our current job and ignore looking for new and better opportunities. Especially if the current job is not as expected, we must quickly find another alternative job.
OP's advice is only true if we have a stable and high-paying job, then it is true that we should spend most of our time focusing on that job to produce better results.
In general, improving our financial situation is a common problem for all of us and each person will have different ways to improve their financial situation. Since everyone has different challenges and difficulties, there will be different ways to improve finances. There is no formula that can make us all rich, we need to be flexible to suit our circumstances.