Day-to-day vocabulary of professional authors?

[Galen L]

I have reading some Stephen King lately and I have just been blown away by his vocabulary. Now I realize of course that we all know words in context that we don’t use from day-to-day. What I am curious about is do professional authors who use such a board scope of vocabulary actually have a similarly extraordinary day-to-day vocabulary? I have little doubt they are of course higher than average, but I wondering how strongly the correlation is. To be frank, the reason why I am asking is that I am interested in trying my own hand at writing and now that I am reading more critically I find myself both impressed and intimidated by all the words I find in my reading that I’d have never thought to use myself. Do great authors such as Mr. King have to grab their thesauruses like the rest of us mere mortals?