Becoming rich is possible as a salary owner though it might not be as easy as it will be for a person with a successful business,but we also have to understand that wealth is relative because what i might consider as wealth could be something that someone else do not consider as wealth
A salarybcan become very rich by investment some of their income on good investments,the more investments a salary owner invests then the more wealth they can create,and also there is nothing stopping a salary owner from owning a business,the salary earner can simply just open a a business and find a good manager to help him or her manage the business since the salary owner will not have the time to monitor the business daily
But another thing is that it depends on the salary of the person,if the person salary is very small then it might be very difficult for them to become. Wealthy except if they get a salary increase in the future