I recently learned that there is one wallet in the world with 1 million BTC attached. Who do you think it could be?
Its safe to assume that this is just a mere speculation. How could you say you'd learned it as we can checked the blockchain explorer for those top wallets holding tons of bitcoin doesn't have a wallet with million accumulation alone. That's gonna be a huge money and a person holding a million of BTC is gonna be a top position to either dump or pump it on market.
If there is one and that is ko other than Satoshi but he surely dispersed it through different wallet as precautions.
That's because there is a difference between "wallet" and "address" in bitcoin. We have no way of knowing how many wallets they are, how many addresses a certain wallet contains and how much bitcoin that wallet has in total. All we can see from the blockchain are addresses and their history (also their balance).
OP and some others replying are confusing these two concepts. Also there is an old
guess that later on turned into FUD that Satoshi holds 1 million bitcoins which is what OP has heard.