I wouldn't care about the overall number of users, just the number of users in the market that I'm targeting. The creative market didn't abandon Apple when the overall Mac market was in dire straights because the market they cared about still had a lot of Mac users.

From what I can see, the consumer market for software is basically dead. Is anyone making serious money on non game personal computer software besides Adobe and Microsoft?

The smaller Mac only software companies are going by the "thousand true fans" strategy. Stay small and get a small loyal customer base.