Don't make the comparison based on price alone, because if saving money is really all you care about, you're going to end up disappointed with either one if you don't adjust your expectations about what you want from your coffee. The French press is cheaper in the long run, that's clear, but there's a detail most people leave out: you need to grind your coffee at home if you want it to be worth it, because ground coffee loses its essential oils pretty fast and what you bought fresh a week ago is already stale.
The real trap is that if you switch from Nespresso to a French press just thinking about saving money, you're going to end up investing in a decent grinder (which isn't cheap), and then you'll probably want better quality coffee because the French press amplifies both the flaws and the strengths of the bean. In the end, a lot of people who make this switch spend about the same or even more because you get hooked on specialty coffees and all that. If your brother is happy it's probably because he enjoys the process, not just because he spends less.
That said, if you're interested in experimenting and you've got some patience in the mornings, the switch can be genuinely satisfying. The quality of coffee with a French press is objectively better if you use good fresh ground beans. But if what you really value is the convenience of popping in a capsule and having your coffee in thirty seconds without thinking about anything, the Nespresso is still better for that, even if it costs more. It's not just about money; it's about what kind of experience you want every morning.