It's pointless to argue with someone about their lack of belief in gravity (where "gravity" is a metaphor for any obvious known fact). Better to let them fall, and learn the lesson the hard way.
If I see someone following a failing strategy and I can help, I will advise them exactly once. If they ignore me and continue, I let them fail. Remember someone else's stubbornness is not your burden.
The fact is in this life, we all have limited time. As a leader, I love to spend some of my time on mentoring, but I will only invest that time on an open mind. An open mind is a prerequisite for learning, after all you cannot teach someone who already believes they know everything.
A stubborn person will often hold onto a bad strategy until it hurts them, and even hurts the people around them, including you and your teammates. In those extreme examples, it is not just about letting them fail, but let them fail as far away from you as possible.