Time I'm investing in developing Ethereum led me to work on state of the art cryptography, acquire advanced peer-to-peer fault tolerant computing concept, exposed me to formal verification techniques, writing code expecting an hostile environment, thinking about economic incentives and game theory.

Social networks, banking and cloud companies would love to hire for those skills.

Also central banks now want to do CBDC (Central Bank Digital Currencies), so skills acquired as dev/builders are and will stay in very high demand for the foreseeable future.

You could say the same about startups on general

Are there any decentralized companies on ethereum making a steady income for people who invested in them?

Maker, YFI, Aave just to name a few. https://cryptofees.info/ lists the real cash flows of protocols.

I'd say that is a positive aspect. It means a lot of things are being tested. Most fail but at some point they might create something awesome that sticks.

ICOs? or smart contracts broken by never-ending hardforks?

Both