That's not the question the investor was asking. He was asking whether to invest in Founder A or Founder B. Suppose A gets their happiness from a baby - this makes them happier and more fulfilled in their remaining 50-60 hours/week. Founder B gets their happiness from marketing - this makes them happier and more fulfilled in their remaining 50-60 hours, plus they spend 20 extra hours on marketing.
All else held equal, B is a better investment than A, even if A+baby is a better investment than A sans baby.