The available data[1] suggest that society at large benefits from increased productivity regardless of whether the individuals driving that productivity are 65 or 25. Fortunately, we live in a positive-sum economy where working harder and longer not only grants you a bigger slice of the pie, it increases the size of the entire pie itself.
Be careful extrapolating macro scale effects into the micro scale. GDP is a function of a huge number of things and its correlation with positive outcomes doesn’t mean everything that boosts GDP is a net positive. Many forms of economic inefficiency end up boosting GDP.
[1] https://ourworldindata.org/grapher/gdp-vs-happiness