As a cryptographer I can't stand this quote. Nothing against Neumann, but the people who choose to spread it as sage wisdom really only manage to convey misinformation. In context it is a superfluous philosophy quip.

We have had fast reliable cryptographic random number generators for decades. They really do work with just a tiny seed and a bunch of arithmetic. The numbers produced are indistinguishable from any other proper random source, and they work for any purpose.

Too many people don't understand this, and entire companies are founded on selling snake oil true random.