How much do you earn with Ethereum node?

I'm curious to understand the potential earning opportunities with operating an Ethereum node. Could you please elaborate on what factors contribute to determining the amount one could potentially earn? Is it solely dependent on the number of transactions processed or are there other variables such as network congestion, node performance, or the type of node being operated? Furthermore, what are some common strategies or best practices to optimize earnings while maintaining a secure and stable node? Thank you for clarifying these details as I am interested in exploring this area further.