An old work friend had been in one. I's interested so asked lots of questions. I got few answers, and got the sense there was one investor, and the other people didn't learn a great deal or contribute in a meaningful way, but of course their funds, and decisions were voted on. It was a legit investment club, and she apparently gained a little money.
I thought the point of those things was to learn a bit about the market and stock picking, have some fun, and hopefully make some money along the way.
But if the reality is one knowledgable person leads, directs, and influences the group without any learning component then its almost certainly not better than an ETF that tracks the market, and any added value gleaned from a better personal understanding is lost.
So whats the point? If you just want to track an investor, i think etoro does that. Quiver quantitative tracks US reps and senators which for some unknown reason often beat the market... ... ..