Where is the link between the graphical analysis (investors as a whole are bad at timing the market) and the subsequent quotes, (e.g., Bogle saying "I do not know anybody who has done it successfully and consistently. . . .")

It is a far cry from knowing that investors _as a whole_ don't market time well, but that has nothing to do proving that some skilled specific investors might not be good market timers.

For the record, I do think there's evidence out there that does show that even the "best" market timers succeed largely because of chance or luck, but it's not something you can get to from the data offered here. Because there are individuals who do succeed at timing the market. The question is whether they succeed due to skill or luck. . .