You're both right, but you're both speaking casually so it's hard to understand precisely what you're saying. Here's my take on it:
At least from a perspective of early retirement, if you can change your lifestyle so you can sustainably spend less, then (i) while you are working, you can save more money, due to lower expenses, and (ii) provided you are willing to continue living frugally after retirement, you don't need to build up as much capital to fund retirements from investment returns, as your post-retirement expenses are also lower. I think the second factor makes a bigger impact than the former one.
The point you make is also a good one: people with more wealth and resources are in a better position to make longer-term investments, which can help them save or make even more money in the long run.
The two heuristics "spend less" and "earn more" aren't always in conflict, you can often find opportunities that strictly improve one without damaging the other one.
At least from a perspective of early retirement, if you can change your lifestyle so you can sustainably spend less, then (i) while you are working, you can save more money, due to lower expenses, and (ii) provided you are willing to continue living frugally after retirement, you don't need to build up as much capital to fund retirements from investment returns, as your post-retirement expenses are also lower. I think the second factor makes a bigger impact than the former one.
The point you make is also a good one: people with more wealth and resources are in a better position to make longer-term investments, which can help them save or make even more money in the long run.
The two heuristics "spend less" and "earn more" aren't always in conflict, you can often find opportunities that strictly improve one without damaging the other one.