There are tiers of KOLs in pain I think. There is a rarefied top tier includes a small number of people with their fingers in multiple pots, likely consulting for multiple VC/investor groups, and are capable of moving the field in a direction they choose based on devices/studies/etc. These people pop up at the top of every feed and have run a few societies. I suspect there are instances of devices and drugs that have died at their hands, and others that have succeeded because of their involvement. There are a ton though who are just trying to climb that ladder below them.
It is important to accept that not all KOLs are in private practice. Many are in academics and prefer the "purity" of the AMA/NIH/ASA/AAPM/SIS/etc. Their tiers/metrics are measured by publications, committees like the AMA RUC, involvement in organizations/legislation, etc perhaps more so than clinical acumen or case volume. Their connection with fellows is a selling point and their reputation is built slightly differently, but it's the same idea.
All KOLs are marketing themselves and their product is their opinion as well as their reputation. There is a bidirectional flow there with devices, procedures, and therapies. It's not as clear cut as putting athletes on Wheaties, but reputationally things are connected.
All these KOLs get together and affect physician practices by distilling their shared opinions in the publications of guidelines/statements/etc
