Why Proving Ethereum full consensus?

Compared to Ethereum light clients, the approach of proving Ethereum full nodes has much higher security guarantee. Ethereum light clients operate on a distinct algorithm, and their security relies entirely on a committee known as the “sync committee.” However, the sync committee’s size is merely 512, rotating roughly daily (i.e., about 27.3 hours). The total staked assets amount to as few as 16384 ETH (calculated as 512 * 32), a figure quite negligible (~only 32 million USD ETH staked currently) in comparison to the daily transactions volume (more than 300 million USD) on cross-chain bridges connecting Ethereum ecosystem with other networks.
Another issue is that the sync committee does not always sign the block. (e.g., block 17239413 and block 17239414). Statistics show that 1.6% blocks are not signed by the supermajority of the sync committee, and the issue may happen every 12 minutes on average.