I was a BOINC user a few years ago (I stopped when I replaced my computer) and recently got back into it via my newer interest in cryptocurrencies. For me Gridcoin was a no brainer once I heard about it (through a friend not an add) as I wanted to support Boinc anyway so why not get rewarded at the same time? It makes sense to me that the Boinc targeted adds would work so well as they're more about awareness than persuasion