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
No... your calculations are wrong. If you want to purchase
BTC900 in one go, then you need to buy them at a considerable premium to the prevailing exchange rate. Also, if you are dumping the same amount of coins suddenly, then you will get a rate which is lower than the market rate.