What are the advantages for an user that is running a Bitcoin full node?
You validate your own UTXO without any external services that may play for your disadvantage, no middleman needed
It's the most privacy-preserving and secure way of using bitcoin. Lightweight-clients have some privacy issues, not too many people are reviewing their code.
The process of setting it up and using bitcoin core is a major step in one's education when it comes to bitcoin. More knowledge = advantage.
You have some voting power on consensus rules, like in UASF.