 That which goes in always, always mirrors perfectly that which goes out, so it offsets to zero. Your purchase amount, their sale proceeds would cancel each other out in the market's big ledger. Your money in, their money out. The net flow would, as I said, still be zero. And if their desire to sell outweighed my desire to buy, they may even end up selling to me at a discount and the price would go down, even with my new money coming in.