Earlier quoted context omitted.
And..., just like that, you are part of a bot net.
The truth is, nobody personally vets the source of all the software they use. Even people who compile everything themselves aren't reading the source code that came over the wire. It baffles me when people fret over "don't blindly run that curl|bash installation script because security!" when nobody would bat an eye at a .deb downloaded from the same web site.
A minimum amount of care when installing things (checking signatures/checksums, reading install scripts, etc) should be common sense and not doing that is grossly negligent.