Maybe being alone at the top is good for the ego, and some people like that, but it is also boring. If you are at the top in some field, is is probably your passion, something you want to talk about all day, but no one understands you, you feel like you are talking to babies, repeating "obvious" things over and over. On the opposite, you can't find anyone to teach anything new to you, being a pioneer is nice, but if you get stuck, you can't count on anyone but yourself, and it can become tedious.
So, when you finally meet someone on your level, it is someone you want to keep. At last, you can talk with someone who understand you, who can provide a meaningful input, and even teach you a thing or two. And even if there is some rivalry, you have a worthy opponent, not an annoyance.
I feel these meetings work best when there is no career pressure, but when people have aligned goals and just want to make progress. It's easier to leave good points unsaid if everyone prefers having any conclusion to having no conclusion.
Don't hesitate to call others out for their behaviour, as it occurs. And involve those who seem to be withdrawn or quiet, ask them about their opinion and input. It takes concerted efforts, if not coaching and training, to get out of that habit.
Second is the chairman facilitating who didn't controlled the conversation, didn't leave time for bullshit, and probably had a very tight agenda.
Perhaps sufficient greatness of attention span is a prerequisite to remember what everyone has said since the start of the meeting :-)