Investing is an element of wealth creation. I would always advise the majority of people that earning a salary or income won't make them rich or even wealthy. Imagine you are a family man, and at the end of the month you receive your pay, you deduct your tithe to give to God (if you are a Christian), and you give your wife a certain percentage that would covert the household expenses for one month, transportation to work, house rent, and other associated costs.
When you add up all these costs, you will run out of money before the month is out.
A clear investment strategy, patience, and sufficient understanding of the project you are investing in are all necessities when it comes to investing.
What do you mean a salary can't make you wealthy? It depends on what you do for a living and where. If your job is a special welder in Germany for example, that is around 5k/month. That can definitely make you wealthy in only a couple of years.
Now, of course, investing extra income is always smart, but you can live really well without it. Being responsible with your money is actually the hardest part for most people.
You are right though. Well I'm speaking specifically for my my self though..coming from an average home and living in country like mine.