Why was $8 billion in bitcoin moved this weekend?

There was a huge movement from old satsoshi era wallets a few days back.

Why?

(Source: https://cointelegraph.com/news/bitcoin-whale-transfer-not-sell-off-says-arkham-blockchain-intelligence)

We don't really know why!

I assumed they were transferred from old wallets to more secure wallets.

However, some are speculating they were hacked.

What if it was quantum already?!

I would assume they would have been sent to exchanges or mixers if that was the case for either of those...