Is it really as good as you say? Blackrock or Microstrategy or Tesla are all bitcoin investors, which means they don't buy bitcoins just to hold them forever and not sell them. Have you ever thought about them selling all the bitcoins they accumulated to the market and what would happen then? It would certainly be terrible. In the past few days, when the amount of Bitcoin that Grayscale sold was greater than the amount of Bitcoin that ETFs bought, the price of bitcoin also decreased. And even a small amount of bitcoin can cause a decline, so if Blackrock sells a large amount, it will cause a huge panic in the market.
Yes every sell from this big investors will definitely cause a market correction because of the excess supply they have. No investor that doesn’t know this, the market is of two phase the bearish and the bullish. So even if the blackrock decide to sell today which is logical it will still be a good thing because it means more buying opportunity and also a spread of the coin to other investors than them holding the junk of it. If one is scared of a drop then they should sell when they are in profit