There is some truth to this. If you work for someone else, you’re going to get paid something approximating the minimum possible for the job, required skills, etc. As the business grows or generates profits, your income typically won’t go up dramatically. Whereas if you own your own business and it succeeds wildly – which is a heck of a long shot – you can potentially become very rich. Which is probably what the person asking the question means by wealthy.
But there are lots of ways to accumulate wealth while on a salary. Let’s start with the easiest: a really big salary. If you’re making $2M/year as salary, not only do you just have a lot of money, you could easily set aside a majority of it each year and use it to develop wealth through investments. And by almost anyone’s standards, such a person is wealthy. But you don’t need such an outlandish salary to become wealthy. There are a lot of people in the world working for about $100k/year. This by itself puts them in the top income brackets for most of the world, and these people look pretty darn wealthy to someone making $5k. Or maybe even $50k. But some of these people will spend most of their income every year. These people won’t accumulate wealth. Others won’t – they will live frugally, and invest wisely – and may accumulate quite a lot of wealth. I don’t judge either approach – do what makes you happy – but the point is that it is very possible to accumulate wealth on a salary.