How much one donates is a distraction from the actual point.
The point is that these people have made their fortunes using the internet, and probably in no small part the freedoms that exist(ed). Its is not that they are rich, is system on which they got rich. I think many people would feel that such people should donate as a sort of pay back, paying one's dues. The rich part of the point simple suggests that a decent donation would be small fry to such people, and cause them no pain. $5 to some people could be a significant hit to the pocket.
Edit:
Been in garden, letting the subconscious flow, and it suddenly occurred to me that donations from the likes of google and facebook would be a problem. Eventually EFF would be accused of being in google's pocket and all hell would break loose.
Begs the question: how can the likes of google donate to the likes of the EFF with out there being the suspicion of a conflict of interest?
I certainly can write a check for $5 (and have donated more than that), but the thing is, a $1m donation from a rich person does a lot more than my $5 - specifically, it does 200,000x more.
The widow's mite is, in the end, still just a mite.