How do I make peace with parents' poor choices?

My parents are 81 and 78. They live in a huge house (5000 sq with a full basement that IS full) and it is situated on acreage. My dad has had several back surgeries and neck surgeries, both have had knees replaced, and my mother seems mentally ill to me; mean as a snake and lashes out at him constantly. He walks out of the room and rewrites history about her. He suggested to me that he thinks she has Alzheimer's (I don't think she does) but if I suggest he get her to a doctor about it, he brushes it off saying that 'if she gets really bad then I will think about it". If I suggest that it is best managed be addressing it early he just shuts me down.
He on the other hand seems to think all these surgeries are things that are supposed to 'make him like new' so after a major neck fusion or something he is back to climbing up on the roof to clean out gutters or something.
My dad was a successful business man and retired at 50. They built their home as well as designed every detail of it 37 years ago and he was the developer of the whole development they live in. So he thinks of himself I think sort of as the 'king' around there. Biggest home, biggest yard, and he can't imagine ever moving. It would be admitting failure or mortality. So we have accepted that the probably wants to 'go' being the guy who fell off the roof while clearing out gutters. What I fear is that he won't die - he will be permanently disabled but live much longer. However, they are grown ups and they are free to do what they want to do. There are five of us siblings and I am positive this is going to be a hellish situation when the perverbial "you know what" hits the fan. But that's what they are creating. We will deal with it. Meanwhile, as I approach 60 and my husband, who just turned 61, both realize this will be us in 20 years, have decided to take a lesson from this craziness and just make better choices as we age.
My mother in law is 91 and lives in a nursing home, where the food stinks and people who have already lost it are ranting down the hall or sleeping in their chairs. She didn't really have a plan for home care even though she had the means and she lives in a place where good care choices are limited. I don't want this existence either. Pray about it, and then you just have to let it be. Bless you and good luck.

We suffer, sometimes, as we watch our parents make, what seems to us, poor choices. However, unless they are cognitively disabled, they actually do have rights. If they are happier with their arrangement than any other, you may just have to wait. Yes, she'll fall again. Maybe she'll get hurt badly. Or your dad will get ill. There will come a time when changes will have to be made.
But it is there life and sometimes there isn't much we can do. Keeping them safe isn't always the same as keeping them happy. It's tough to watch, I know. But if you can't see any way to change their thinking, you may have to wait until something else does.
Meanwhile, don't badger or nag. However, if they know people living in assisted living homes who are happy, encourage friendships in this area. Sometimes peers can help them make decisions more readily than adult children. Good luck,
Carol