Is it really?

When your income and employment in life determines when (and if) you can retire one day, if you could provide for any children, if you can buy a house, etc.

Also your health and life expectancy is linked to your wealth.

And maybe it even determines if you can get a partner, as many males still need to fit the provider role (either for themselves, as they don't dare to date anyone if they don't; or as the woman they fancy might want more in life and chooses someone else, who can provide for more)