Salary won't never make me rich

I did a rough calculation, if I save $50K per year, I will have $750K saving after 15 years. That maybe my whole career. So the conclusion is I won't never be rich if rely on salary income. But if I can invest and have a single digit return per year, at least my saving will double after 15 years.

So making money from work is basic only. The more future relies on investment return!