This is a valid point. I am a conservative person by nature so I struggle with a more aggressive allocation even though most studies show a future benefit.As gauss said, your budget has to include everything (taxes, medical insurance, new roof, ...). If it does, you are good to go.
You have ~$2M in MMFs. MMFs historically lose to inflation. I would deploy most of that $2M to something that would at least meet inflation. Beating inflation would be better. You will hopefully have a very long retirement. Inflation is something you need to be aware of. Your 66% equity should do the job, but I would not hold that much "cash".
I used mmf because it seemed like bond funds were losing value over the past few years. I realize this is likely temporary and that future rate cuts should cause bond fund gains.
My thought process was that if that if the market crashes 50%, then my balance would change from 6mil (4mil stocks + 2mil mmf) to 4mil (2 mil stocks + 2 mil mmf). This would still be ok for us with 3%swr if we cut our discretionary spending in half. If i held a bond fund in this same scenario it could lose 25% of value leaving us with 3.5mil which is still doable but not optimum.