"Must everyone consider actual evidence before holding an opinion on anything? " David K
Not everyone who holds an opinion has considered actual evidence before holding that opinion.
You think they should
I dont think every opinion requires actual evidence.
I cannot think how depressing life would be for somebody to worried to hold an opinion without having first to read up on in depth evidence and data, I am glad I am free from this burden you obvious carry.
Anyone so cavalier as to offer opinions which impact on people's health and safety based on no evidence is ethically and morally deficient IMO.