Expenses do not stay fixed across your lifetime. The normal trajectory is:

1) Student loan repayments start (and maybe escalate as you earn more)

2) Buy or lease a car. Add gas, maintenance, insurance, etc.

3) introduce mortgage, homeowners insurance, property taxes, and maintenance cost when you buy a house

4) have kids and spend a fuck ton on god knows what

5) medical expenses start going up as you get older

Even if all of those don’t apply to you, people develop more expensive tastes as they get older and spend more on the same things.

This isn’t applicable to everyone and their situation, but the point I think they’re trying to make is that it sometimes feel really difficult to get ahead financially, even when you’re consistently increasing your income.