True, there are lots of factors at play. All things being equal though I believe shyness is a hindrance to being successful both socially and professionally in the conventional sense.

As a shy introvert myself whose even been suicidal in years past, I'm thoroughly aware of the obstacles it presents. However, since becoming a personality researcher, my views have shifted to viewing it more as a net positive for a lot of things, and it's certainly less of an uncommon opinion these days:

https://youtu.be/85s9wJlzkrk

That being said, there are a variety of other character traits that play a role in how different people reach success, thus part of the issue is simply the interpretation of "success" itself, because quite often we look to very specific examples of successful people (e.g. Steve Jobs) or paths, that don't suit our personality taits nor strengths at all, and set us up with unrealistic expectations for ourselves.

Success comes in all forms, shapes, and sizes, so there should be no reason to let certain traits limit us on the hunt for success, when the game is largely about filtering out the noise and focusing on paths and pursuits that actually play to our strengths, instead of ones that make us perpetually anxious and stressed out.

Also shy but I realised fairly early on (early 20's) that you can't be entirely shy and function in a society with people that mostly aren't so I cultivated the ability to overcome it for nescessary tasks but honestly most of the time I'm happier in my own company with a book than out with my friends.

I hear a saying a while back and I'm murdering it but "Introverts recharge by themselves and extroverts recharge with other people" and that is me, in small stints I can be gregarious and outgoing but within a short period I just want to be on my own again, I find it tiring.