USA Today has an article about questionable quotations from technology leaders—if you’ve ever heard the quotation above, or heard about IBM’s founder saying there was a world market for only five computers, or Bill Gates saying nobody could possibly need more than 640K of memory, read the article to see why you shouldn’t believe everything you read.
As for the “Everything has been invented” quote, this is one of those classic misquotations that persists because people want it to be true. Everyone loves to hear stupid words from the past that were later proven very wrong.
Of course, like many such quotations, it’s too good to be true. This one has been misquoted for literally more than a century, and pretty thoroughly debunked as early as 1940. Nevertheless, thanks to the Internet, it persists… Here’s lots more information about this misquote.