They buy a million dollars of Bitcoin, that pumps the price up, they sell a million dollars worth fir thing, that dumps the price down.
At the end, nothing has changed, except they have 'donated' a million dollars to Bitcoin owners.
Besides making some lucky people really rich, wouldn't it make mining not profitable? If I understand how the system works, without mining the entire network is shut down. If a majority of miners stop mining and the difficulty remains the same for the few people who are still mining, doesn't that render the network "dead" if you will? Perhaps i don't understand where the value of bitcoins to USD comes from.