I recently learned that there is one wallet in the world with 1 million BTC attached.

That's an assumption, it's not confirmed. (And it'll never be)

I would say the assumption is wrong... The top reach bitcoin address is public information, and right now the address with more bitcoin is this one: 34xp4vRoCGJym3xR7yCVPFHoCNxv4Twseo with 143528.45848982 BTC

So, 1 million BTC wallet is what we call 'FakeNews' but what is real is the information about how many Bitcoins Shatoshi Nakamoto Has, and in theory, he has a little more than 1 Million.

Sources:
https://bitinfocharts.com/top-100-richest-bitcoin-addresses.html
https://btc.com/stats/rich-list
https://www.blockchain.com/btc/address/34xp4vRoCGJym3xR7yCVPFHoCNxv4Twseo