I'm genuinely curious how much does it cost to operate a node on hive?

The cost is wildly variable.
My node costs $50 a month and earns like $250/m but it's also quite bad and I need to upgrade.
A full node is a lot more expensive as it needs to allow others to connect to the API and serve requests.
A Condenser clone is even more expensive because that's basically providing a website like hive.blog or peakd.com that can allow frontend access to the chain.

It's basically expected that top 20 witnesses should pay more and provide better infrastructure.