Earlier quoted context omitted.
Having to pay to visit all of the sites out there which are currently using ads would pretty much ruin the internet for most people. Having a big banner at the top asking for donations seems to work rather well, though. See gnu.org and wikipedia.org for examples (though Wikipedia's donation campaign this year is a bit excessive IMO).
FYI, you can hide the Wikipedia donation campaign banners by putting this in a userscript that @matches http://*.wikipedia.org/* : setTimeout(function() { fundraisingBanner.hide(); }, 1000);
||https://meta.wikimedia.org/wiki/special:bannerloader