It's pretty simple for you to get a good income "you must be a producer and not just a consumer" I believe this rule is what must people who are entrepreneurs live by, hence must salary earners at some point after accumulating enough savings they result into owning a business but perhaps it's not compulsory to own a business.
Some people who owned business still remain poor so it's not a guarantee that you will be successful (what you call "rich"). If one earns a good or significant amount of money and do not want to own a business investing in others business could still make you a very good return, perhaps being a shareholder is quite a good way to earn as much as the entrepreneurs.
If you only choose to be a consumer, you will be spending all you have for the benefit of others. Because buying of order peoples goods will only benefit the manufacturer or producer of that particular product. But if you are a producer, and you produce a quality product, people will also purchase your goods and services and it will be vice versa. As you are purchasing people's products they will also be purchasing your own, and the equation will be balance. Because both sides will be benefitting from each other. Doing a business doesn't guarantee riches, you need to work very hard to make your dreams come true.
However for the case of people earning salaries, do you think there is a way they can be really rich without owning a business and or is it compulsory for one to be own his own business
It is still very possible for a salary earner to invest some from the salary they earn. It will require a lot more sacrifice because unlike being a business owner that can have access to money and no fixed earning, a salary owner having a fixed salary will need to cut some other expenses to have enough for investment unless the job is very well paying which is not much as well.
A salary earner will also need to be very strategic and careful with what they invest in, so not to waste their salary years on something that has no or very little ROI.
Yeah, it is very possible for a salary earner to invest some of the salary they earned into something beneficial, but it will be very difficult to do so. Must expecially when the person depend only on the salary as the source of income and has a lot of responsibilities to take care of. There is no way you will be wealthy without do something profitable.