Why are roughly 95% of colour blind people men?

This is because the most common type of colour blindness is caused by a gene located on the X chromosome. Since men only have one X chromosome, even one faulty gene is enough to cause colour blindness. However, women have two X chromosomes, so a working copy on the second chromosome usually compensates.

A woman can be colour blind if both of her X chromosomes carry the faulty gene. This usually means that her father is colour blind, and her mother is at least a carrier of the gene. Since this combination is much rarer, colour blindness in women is uncommon.

https://enchroma.com/blogs/beyond-color/can-women-be-color-blind