I'd like to preface this with the fact that I do donate time, money, and on occasion PRs to open source projects.
But frankly, I don't believe anyone has any obligation to donate to an open source project.
I also don't think anyone has any obligation to give 8% of their revenue to a project that's completely under the control of a man that ALSO runs a commercial entity extracting money from the same project.
And I REALLY don't think you have any obligation to give a guy worth $400 million one damn cent for using his GPL-ed software.
It's not like he's going to take the money and give it to the people in the community developing it, it's going to go into his business - and thus right into his pockets.
This is just CEO corpo greed, and frankly, screw Matt. He has enough, and if his business is falling over because he got greedy and got into bed with VC and bought a failed social media network, well, that's his problem and not everyone who uses Wordpress'.