I only know from the past. I don't know how it's changed since though. But that's how Gavin was paying us (and himself) back then, with grant money. So I'm going to assume it's still their main source of funding.
Gavin gets paid by the Bitcoin Foundation who in turn got paid by their sponsors. What grant are you talking about? first time I ever heard of it, can I get one too?
Mike Hearn was a senior engineer at Google and co-owns a number of anti-spam patents with Google. Google lets certain employee's spend 20% of their time working on any project they want, Mike choose Bitcoin as his project in 2011. He quit his job in 2012/2013 to work on Bitcoin fulltime and is now paid by the Bitcoin Foundation, significantly less than what he was paid at Google.
Thats not to say there isn't a financial gain. This change could have impacts on mining revenue, it's hard to know for sure whether they have a financial reason for doing it. I think their reason is probably desperation but also a grab for more control over Bitcoin, the blocksizelimit does need to be changed but not via the insanely dangerous way they are attempting.
as well as gaining 260k + a year from the bitcoin foundation of awhile......so yeah good to see we've got an alternative to those greedy bankers 
