You can actually extract a VI from an EXE, but there is a very good chance it won't be useful at all. If you did not enable debugging when the VI was made then you will get a VI with no block diagram, no front panel (in most cases) and no source code. This VI will be a thing that can be ran, but only in that one exact version of LabVIEW it was made for. There will be no VI icon, no description, and possibly no terminal labels (it's been a while since I've done this so I can't remember). This process of pulling a VI out is not like a decompiler. The output isn't like source code, it is more like a DLL that is still binary and still compiled for a specific platform and target.
tldr; what infinitenothing said.