I've used Cassandra at two companies, and had the exact same experience as you at the first company. At a much bigger company that had some very, very highly paid Cassandra DBAs it was actually a relatively smooth experience.
If you can't magically put out production fires, on huge high-throughput systems, potentially in the dead of night, we are unlikely to pay you $300-400K.
My career has been primarily focused on something like “bringing modern data-driven solutions” to big companies. The one thing that is a constant challenge is that most teams (and leadership) aren’t prepared to handle responsibilities of data engineering and stewardship in transactional, operational systems. I feel like critical responsibility when I come on as a consultant is to impart knowledge about managing their data.
Distributed databases are pretty difficult to manage, they deserve every dollar.