I don't care what the full nodes do, it is irrelevant to my [implicit] question, which is: What makes you believe there's any correlation between nodes & BTC wealth?
Your question is generic and open ended and can be interpreted in multiple ways. So I will take a stab at explaining different aspects. A node is indeed relatively cheap to produce and maintain, but nodes without economic intrest are valueless just like anything in life - fiat, assets, stocks, ect..).The reason why certain nodes are more valuable than others is because the network effect. A single user behind a full node with an active wallet is more valuable than a userless ec2 node because the node is being tested for bugs and has a real economic actor behind it that can make both economic decisions as to assigning value to items and the consensus rules within his wallet. A node controlled by a processor /wallet/ merchant has a greater value as they have a pool of users interacting with their node and thus conforming to their consensus rules.
When you say "valuable," valuable to what/whom? All nodes validate & relay transactions, so how does the network know (and why should it care) about how much BTC the node's creator has? A node is a node, it validates according to its ruleset, no more no less?
Here is an analogy to consider:
What is worth more: 5 large fortune 500 companies(these companies can be represented by humans and code alone and don't nessesarily need to sell a physical good) and their userbase that enjoys their products and services or 100 shell companies with no capital, no products, and no users? What happens in an ecosystem when these 100 shell companies are introduced to a location and the general public chooses to ignore them because they don't like their product?
How does the network know how to value a node? I must be missing something very basic.