Hobby, hobbier, hobbiest hobbyists

I’m making my way erratically through Robert Crais’s back catalogue of detective fiction, and today in Demolition Angel (Orion, 2000) happened upon an unusual misspelling:

Hobbiests! I almost read right past it. But once a proofreader, etc.

Obviously it should be hobbyists, meaning people devoted to a hobby. Hobbiest looks like a superlative adjective – “the most hobby”. But the two words are pronounced very similarly or identically, and many more words end in –iest than –yist, so you can see how the non-standard form might have materialised.

Although hobbiest has yet to appear as a variant spelling in any of the major dictionaries, a Google search shows it to be common in unedited writing. This is the first time I remember seeing it in a published book. Proofreaders, en garde: lobbiest may be next.

Edit: Here it is again, later in the book, this time in the singular.