Would you really have a low opinion of someone who spent that much time, personal energy and their own money on a project, to make you some open source software, for which they give you all the freedoms but ask you to not jeopardise their ability to continue if the only reason you have is "because you can"?
Do you think it's wrong of Red Hat to sell Red Hat Enterprise Linux? Even though they pay the full-time salary of half the Linux kernel developers, a fair chunk of GNOME developers, and everyone knows you can get a free version, compiled from the same source, from CentOS?
Sounds to me like you have a particular idea about how these things are done, and aren't particularly informed yourself about the various ways FOSS is sold ethically (at least, by some people's standards ethical). Have you ever read the GNU Manifesto, or the FSF's position on selling free software?