Obviously the advice in the OP's post is directed to people who at least have any regular income allowing them to survive and have a little surplus on the top.
If one doesn't earn enough to meet daily needs, he should be focusing on finding a steady income in the first place and worry about all other things later.
That's the problem and people need to think about a fixed income structure when they want to see their finances become much more stable. If they cannot meet their daily needs well then how can they possibly talk further about investment. The main focus must be on how a person can generate a steady income and then try to invest responsibly with a portion that can be adjusted to existing income.
By all means, investing in own business or investing in own qualifications/skills that will help you increase your earnings is also investing. And even if you're short of money, you could still invest your time (aka your most valuable asset) to learn something useful.
We are talking about investment in the crypto space because talking about investment now people will shift their focus to bitcoin. If we develop a business, we should look at our skills to see whether we are able to run it or not because if we are forced to run a business that we are not good at, it will be difficult to develop. When faced with a lack of money, it is necessary to look at how we can take advantage of the existing possibilities because selling assets will be a little riskier.