Vitalik: Due to security staking involving multi-signatures, only a small amount of ETH was staked

ChainCatcher message, Ethereum co-founder Vitalik Buterin stated on the Bankless Podcast that he does not stake all of his ETH, but only stakes "a relatively small portion," as securely staking requires multi-signature, which is still a tricky process.

In addition, Vitalik also suggested that "if you want to stake ETH, the keys to access it must be publicly available on some online system. For security reasons, it must be multi-signature, and setting up a multi-signature for staking is still quite difficult. It becomes complicated in many ways." (source link)