I've run dozens of marathons, multiple 100 milers, and several 12-hour and 24-hour events. You can be the strongest, most prepared person in the world, and it very much might not matter because of how many things can go south in such an event compared to shorter races.
Yes, these events have fewer participants, but nonetheless, even at the most of elite of these events, sometimes women win, and it's not always because the best man didn't show up that day. Big's Backyard Ultra attracts the best in the world, but it was won by a woman in 2019 and 2020.