“You can't go around building a better world for people. Only people can build a better world for people. Otherwise it's just a cage.”

As quoted in "Will the New Congress End U.S. Allegiance to Saudi Arabia and the War in Yemen?", interview by Sharmini Peries, in The Real News (6 January 2019)
2019

2000s, 2001, I Can Hear You, the Rest of the World Hears You (September 2001)

Misattributed

Letters to David Skrbina
The Road to Revolution (2008)

Credited to Shaw in the lead in to the mockumentary C.S.A.: The Confederate States of America (2004) and other recent works, but this or slight variants of it are also sometimes attributed to W. C. Fields, Charlie Chaplin, and Oscar Wilde. It might possibly be derived from Shaw's statement in John Bull's Other Island (1907): "My way of joking is to tell the truth. It's the funniest joke in the world."
Another possibility is that it is derived from Shaw's characteristic of Mark Twain: "He has to put things in such a way as to make people who would otherwise hang him believe he is joking."
Variants:
If you are going to tell people the truth, you'd better make them laugh. Otherwise, they'll kill you.
If you're going to tell people the truth, you'd better make them laugh. Otherwise, they'll kill you.
Disputed

F 39
Aphorisms (1765-1799), Notebook F (1776-1779)

JWZ
http://www.jwz.org/doc/groupware.html
Groupware.