I believe that at several times Apple was selling more in $ than the clone manufacturers, because the clone market was divided among so many companies.
In the mid and late '80s, when I would advocate a Mac purchase, the response I got from many was - "Will it run Lotus 123 and WordStar (or WordPerfect)?" - "No," I'd reply, "but there are equivalent programs for the Mac." "Oh, but I'd have to buy those, I'm just going to copy the programs I need from the office."
So, my hypothesis (untestable, I'm afraid) is that software piracy gave the PC clones their initial boost into the home market.
Can Macs Dominate the Personal Computer Market?