If you haven't moved coins off the exchange you aren't a bitcoin investor.
"You aren't a real real estate investor if you buy the brooklyn bridge from a guy on a streetcorner in Harlem" is true because the claim on the bridge was never credible, not because you never physically took possession of the bridge itself. You could argue that the exchange's IOU was never credible, but that's different from saying that any BTC-based IOU is made of lies.