Without enough sovereign nodes, miners and corporations could collude to push changes that benefit them, not you. Verifying your own transactions is step one, but the bigger picture is protecting the entire network from creeping centralization. Every independent node strengthens that defense.
Discussion
One can spin up 100000 nodes but it really does not make a difference between just running a one node.
By running a node you can protect only yourself and your transactions, others have to run their own nodes to protect themselves.