When Archive.org is missing something, like the Voltz Wars Series by D_2the_avid, I am inclined to donate, so that it can archive more, and such content will not be lost to time. When it automatically archives something I don't expect, like big files on my website, I also feel inclined to donate, because the scale of that is just… amazing, and I am very grateful that it can archive even a site as small as mine.