It seems to me their mandate is to make everyone's lives better. This looks like a project to define web standards for the future. It also looks like they've got enough to last them for a bit.
$100 million is nothing. People regularly win that much on the lottery. It's enough to do amazing things, but not enough to competitively do amazing things.
They're looking to the future, not what is possible but what should or could be possible.
I'd much rather have Mozilla working on an "OS for the web" than Google, despite whatever problems Mozilla may have.