I am also curious about what happened if Grayscale will dump those Bitcoin in the future?
That was my first thought after reading the OP. It wasn't "Wow! Look how much bitcoin this asset management firm is buying!", it was "Just wait until there's a panic and everyone wants to dump their bitcoin all at once".
If that were to happen, I'm not sure how Grayscale would handle the sell order requests. I would hope that they wouldn't just dump a large number of bitcoin onto the market all at once, and I'd also hope that they employ some kind of hedging strategy to protect their customers from bitcoin's notorious market volatility.
If those amount and figure indeed bought bitcoin there should be a massive pumped as the volume of bitcoin will be drag up. Seems like grayscale bought on another way or via otc on some popular platform.
Another post said they were buying it directly from miners, which would be off-exchange, and that's smart. I don't know much about Grayscale, but on the surface from what I've read here it seems like they know what they're doing.