And $3500 per month is not what a lot (most?) people here would consider a successful financial model even given some consulting etc. on top of that. It depends on where you live of course but bringing in $50K per year (with no benefits) or so in donations is not something a lot of professionals--especially those qualified to work for major software companies--would consider a sustainable income stream.
https://www.patreon.com/sindresorhus
but he's kind of a unicorn (pun intended). I am sure this would not work for everyone.