It doesn't matter how much someone donates, if people don't post then there is no community.
Just because one or so people post more than the entirety of the rest of the people doesn't mean that if they stopped, the community would altogether.
Not at all, but for community building it relies as much on people taking part in the community (i.e. posting) as it does on funding.
Funding can be obtained from online advertising (which GH has managed to avoid).
Community membership can only be obtained from posting.
And there will always be some who post a lot, and some who hardly post at all.