The point I'm getting at is that it's a spurious, modern "quote", and it's exceedingly popular among leftwingnuts but not among Republicans and Conservatives.
Hmmm. If you Google "The definition of insanity" you get 198,000 references, the overwhelming majority of which attribute the quote to Benjamin Franklin (though there are a small number which instead credit Albert Einstein). Based on the evidence, it appears likely that it is a legitimate 200+ year old quote rather than a spurious modern quote. As to its popularity, I do see a lot of left wing sites quoting it, but also plenty of right wing sites.
It seems like a fairly logical proverbial saying, which is why I used it myself. Do you have some objection to its contents, or do you just exhibit an automatic visceral rejection of any saying which has every come into contact with a leftist?