Guys, you really need to understand this concept: nodes and validators!
Light clients only download block headers. When they need data for a particular transaction, they request the data and a Merkle proof from a full node.
Client diversity is very important: if the vast majority of nodes use the same client, a vulnerability in that client could affect the entire network.
On Ethereum, becoming a validator requires staking at least 32 $ETH .
Save this and take your time reading

#ETH