I must confess, that for many years I myself thought it meant to move one decimal point to the right, i.e., reduce TO 10% (90% attrition) rather than to reduce BY 10%.
I suppose it was because of the way I heard the word used through the years... carelessly. Which, goes to prove your point.
Well anyway, I take consolation in the fact that I always get the usage of effect and affect right, LOL.
I read a lot when I was a kid and ran into words that I took meaning for from context and figured I knew them thenceforward. One such was a word I assumed to be pronounced my-zld that obviously meant “confused.” I was long an adult before I figured out that the spoken word “misled” that I heard and used in speech was that other word that I only knew printed. I told my adult daughter that and she confessed to misreading the word idiot as idoit(eye-doit)as a young child and thought they were two different words for years. Now both of us sometimes refer to someone as a poor my-zld idoit.
At least you knew and know what the roots imply. That is not taught in public school now. That along with look-say reading gives America generations of inarticulate illiteracy. Wife is a just retired public school teacher. She talks about another teacher that used to educate her students to Latin roots and made them memorize times tables until she got told she would be terminated if she did not get with the modern program. Wife stayed with elementary Spec Ed which is pretty much ignored by principals and school boards so she was able to teach actual academic stuff to her k-3rd graders. The ones who had enough wit to eventually “mainstream” were light years ahead of their mainstream classmates in reading and calculation and wife got some flak for that.