It's gonna be hard especially if the amount is so huge but it doesn't mean it's not possible. It could be done even if addresses and the movements of the funds are under tight surveillance. But it definitely needs a lot of ways. A combination of DExes and mixers and anonymous coins and even centralized exchanges could be explored.
This is the point that remained ambiguous after reviewing the various opinions, and it seems that it is indeed the most difficult task for the thief, even if the robbery was successful.
When the amount is large, centralized platforms will doubt the volume of transfers and look behind its owner, and of course this represents a major risk, and decentralized platforms do not have enough liquidity to make huge transfers.
The most important thing that can be concluded, Bitcoin is the most secure method due to the nature of its protocol, which facilitates the way the mixers work.