Our RTO mandate killed our best hire

we lost maria last week. 9 years here. principal engineer. she'd been remote since 2020 and the new 4 days in office rule was non-negotiable per HR. her new place is fully remote, +35% comp, and she gets to keep her morning with her kid. the cost of replacing her is gonna be like, 18 months of ramp. minimum. and we already know 2 other senior people are quietly interviewing. leadership keeps saying culture suffers without office time. ok fine but what's the cost of losing your top 10% to prove that point. nobody on the exec team seems to be doing that math out loud.