if one million dollar only buy bitcoin is danger investment
If you have 1 million follar, you could purchase around 900 btc or more with the current price and could you imagine what you can do after that?
You can go back selling it because by purchasing 900+ btc you are already pushing its price up therefore that means you are already getting profit from the speculation that you have done
Obviously, this is bullshit
If it really were so, you could just as well claim that after you sell those 900 BTC, the price should go down (just like it should allegedly go up when you were first buying the coins). Then you could easily repeat steps 1-2 and ultimately earn infinite profits. In reality, though, even if the price goes up after you buy 900 coins (which is a shaky assumption itself), the market will be razor thin (I mean the Bid side), and you won't be able to sell 900 BTC at higher prices. You would need to fill the orders way below your entry point if you want to sell them all just like you would have to fill the orders significantly above the market price to buy these 900 bitcoins in the first place. And I don't yet take into account spreads as well as trading fees