I helped someone buy $150,000 worth of bitcoin in the last two weeks, and it made such a small blip on the charts you'd hardly have noticed.
Agreed. We sell our excess "coinflow" to larger buyers (who prefer off exchange transactions). We do at least one or two six figure
transactions a month and it is a "drop in the bucket".
Also to the OP "plan". Anyone rich or powerful enough to move the price simply by announcing (i.e. a CEO, hedge fund manager, Warren Buffet, etc) would need to buy a LOT more than $100K. For those kinds of people only buying $100K would be seen as a joke or gimmick. The ultra rich aren't really interested in trading their "good" name for a gimmick.
Still liquidity and depth are improving almost monthly. Six months ago I would have been shocked if someone asked for 6 figures worth of BTC today it is routine (good but routine) news for us. Haven't seen a seven figure deal yet though. 6, 7, 8 ... it will all happen in time.
Time is on the side of Bitcoin, the longer it lasts, the deeper the market gets, the more the transaction volume the harder it will be for informed people (and yes most of the "rich" are informed) to ignore it or pass it off as a stupid ponzi.