Every current homeowner is a future seller, and every housing unit gets sold and resold over time. Whether a property currently houses school-age children or not is irrelevant to its market value. Local property values reflect the aggregate demand of buyers, including buyers with children needing schooling and buyers who intend to have children. So an implicit demand for schools is reflected in the market value of every residential property...
Communities with good schools will have significantly higher property values than the communities with bad schools. Thus good schools benefit homeowners.