Matt Mullenweg, the WordPress lead, has the following to say on this question.
Someday I think there will be a realization that the real story is more exciting than the cookie-cutter founder myth the media tries frame everything in. It’s not just one or two guys hacking on something alone, it’s dozens of people from across the world coming together because of a shared passion. It’s not about selling out to a single company, it’s dozens of companies independently adopting and backing an open source platform for no reason other than its quality. I’m not a millionaire, and may never be, but there are now hundreds of people making their living using WordPress, and I expect that number to grow to tens of thousands. That’s what gets me out of bed in the morning, not the prospect of becoming a feature on an internet behemoth’s checklist.
Finally it’s not Web 2.0, or another bandwagon me-too content management system with AJAX, it’s a mature project that has been around and grown up over four years of hard work, and it has many, many more years of hard work ahead of it. I smile these days when I see WordPress referred to as an “overnight success,” if only they knew how long an overnight success takes.