It is not worth you stressing about it.
Occasionally you get a snappy email.
Be nice. Their world view doesn't have to be your world view.
Be neutral and negotiate your way through it.
Some people are sensitive about stress.
Don't press their buttons.
With all my experiences buying, on average I still come out happy.
Sometimes you get cost burned, sometimes you get cost lucky.
Treat your losses as simply a business expense and your wins as a bonus.
My experience over years is that I have always ended up coming out better off.
The negatives amount to a very small single figure percentage.