A Plethora of Titles

I was looking on Amazon at books on "Writing" and was amazed at the huge variety of titles available. It seems like writing is a popular topic. Are there really that many people who want to be writers? Or do folks who want to write just read a lot of tip books? I wonder if there are any good "titles" left unused. I know I thought I had quite a few different writing related books but there's no chance I'm ever going to catch up with what's available. So, those of you who read such works, what are the best ones out there. Personally, two books that I've found really helpful to me are William Zinsser's On Writing Well and Lawrence Block's Telling Lies for Fun & Profit. I also have King's On Writing, and Orson Scott Card's book on Writing SF and Fantasy, both of which had some good stuff in them.