Question

Why might an employee contribute to an employer's retirement plan that offers matching contributions?

to comply with mandatory regulations regarding retirement savings
to avoid penalties for not participating in the company’s benefits program
to ensure job security by demonstrating financial responsibility
to double the amount saved without increasing the employee’s contributions

Answer 1

to double the amount saved without increasing the employee’s contributions

An employer match is effectively “free money” — by contributing up to the match, the employee increases their retirement savings without putting in extra of their own pay (and benefits from tax deferral and compound growth).