That isn't entirely fair. There are some websites that offer a free tier in the hopes that enough users will buy the paid tier. I suppose one could call this a

That isn't entirely fair. There are some websites that offer a free tier in the hopes that enough users will buy the paid tier. I suppose one could call this a form of advertising, but Dropbox giving me 2gb free does not seem to the type of manipulative advertising you are referring to (and is not a revenue source for them).