Big companies tend to be somewhat older companies. The people who run them tend to be older. Older people have had a longer time to adjust to society, open up, get out of their shell. People who run large companies also end up adapting to social contact, which is not something we tend to define nerds by. That is all amplified by social media and youtube which help scale up interpersonal examples for people to adjust to for good or for bad.

Some subset of these big companies will be run by people who appreciate that they're having an impact on society and feel that it's important for them to be more public so people can better appreciate who they are. Jeff Bezos was a bit awkward in the 1990s, Bill Gates was way more awkward back then, oh man, it was physically uncomfortable to watch him in interviews. Mark Zuckerberg was absolutely out of touch and forcing himself into the spotlight of his company was a disaster, he rolled -1000 charisma. They had to get Elon Musk to make dice just for that to be possible.

Most of them get better over time. These are not people that generally started hugely confident in public or with lots of people, but when you run these companies you gain both confidence and money which make public appearance less painful. You could argue they might sometimes veer into overconfidence to make up for confidence slipping, which can also be seen as ego.

There are plenty of nerds out there. Statistically based on population growth and also increases in autism spectrum diagnoses, there are more than ever.