“It’s easier to fool people than convince them they have been fooled.”
Seems appropriate for these times…
[sup]*(Or so it says on the Internet, so it must be true - right?)[/sup]
There does seem to be some doubt.
But by G-d, he should have said it.
I haven’t read everything by Twain, but I’ve read quite a bit (including all three volumes of his recently-released autobiography, of late), and this just doesn’t sound like him. I certainly don’t recall ever coming across it, and it’s not his typical phrasing.
A quick internet search shows that a lot of places cite it, but not one gives where it comes from. This does not increase my confidence in its authenticity.
I’ll give this one a Questionable at best, but I think it ain’t one of his.
Every lame quote gains traction, once it is attributed to Mark Twain, Benjamin Franklin, Abraham Lincoln, Winston Churchill or Yogi Berra. But those five philosophical giants actually said very few of them.
This site can’t find it in Twain’s writings, and doesn’t believe it, either:
Wikiquotes doesn’t really buy it, either:
https://en.wikiquote.org/wiki/Talk:Mark_Twain
(Halfway down, under “unsourced”)
This site claims the quote was first popularized in 2011:
http://www.barrypopik.com/index.php/new_york_city/entry/its_easier_to_fool_people
I certainly draw a blank typing bits of it into Google Ngram Viewer.
Google Answers says “n”. as well:
(It also cites one of the sites I give above)
Even Yogi Berra admitted, “I never said half the things I said.” 
Don’t get them started!
I didn’t even look it up but I figured there was a good chance it wasn’t said by Sam - thus my tongue in cheek comment. I mainly posted it because it reminded me of the republicans. It just seemed the perfect sentiment.
Google the search terms /quote fool/, you’ll find that there’s a perfect sentiment born every minute. Even Bartlett’s Familiar Quotations has 90 of them, all pretty applicable to the current condition.
It sounds better in the original [del]Russian[/del] Klingon.