Decreasing term insurance is most commonly purchased to:

Explanation

Decreasing term has a death benefit that declines over the policy period, which pairs naturally with an amortizing debt like a mortgage whose balance also falls. It builds no savings, so it is not a retirement vehicle. A benefit that grows with inflation would be increasing term. And a lump sum for education would be better matched by level term or a savings vehicle. Matching a shrinking benefit to a shrinking obligation is the classic use of decreasing term.