As the article says, stagefright has not been extensively studied despite affecting nearly everyone to some degree. Including some famous people you wouldn’t imagine.
I have feared speaking in front of an audience since I can remember. In grade school I would simply accept a failing grade rather than go in front of the class. I did better in high school and college but still hated it. At work, I avoid it whenever possible. But it never goes away. Since I practice karate I have to be evaluated from time to time and I fall apart, losing track of katas I know down pat. I play guitar but almost never with anyone but my teacher and maybe one of his other students.
Here’s a perfect example of how it affects me. A few years back a friend, who is active in the local music scene, organized a jam session at a local place and invited a bunch of players he knew which included me. I hesitated but I did eventually pack up my guitar and headed down. I was scheduled to go up on stage a bit late so I had the opportunity to observe the others. It was obvious I was the only one with no stage or band experience. The guitarist up before me had just led a long jazz funk fusion number when I was called up. But I realized that I was both way in over my head and scared to death. I made a lame excuse about it being late and having to go to work in the morning, packed my guitar and ran from the building.
I’m a grown man with over 30 years as a volunteer firefighter. I walked into burning buildings and pried broken cars apart to free people and yet I ran from the opportunity to play guitar on stage. That, my friends, is how powerful stagefright can be.