Because it implements the moral ideal of self-sacrifice to the needy.

WSJ: Is Rand Relevant?

The ideal person would still seem to be someone with composure, a self-controlled specimen of high esteem.

FORBES: Millenials Must Stop Advertising Their Insecurity And Incompetence

The new law exempts employee contributions from the 25% of earnings limit applied to employer contributions, making a 401(k) ideal for a self-employed person who doesn't earn a lot, but can save a lot.

FORBES: Self-Employment