Pretty much every company I’ve been in or know of values a vertical trajectory instead of a horizontal one for its employees i.e becoming a manager nearly always means a faster salary progression than becoming an expert in one or multiple fields.
Why is expertise valued less?
I have worked for one truly amazing leader in my time. He earned my complete 100% trust and commitment. I don’t think its possible to fully get the value a leader can bring to a team until you have a really good (or great) one.