It's a fine line. You can certainly create an investment club privately amongst a group of friends or coworkers and create an LLC where every person is a partner and has an equal share. That seems perfectly legal to me but soliciting investment on Instagram and offering a market for partners to sell shares externally seems questionable.

Also when you get into holding assets like golf courses, real estate etc that are not passive investments I think you are also delving into potential issues. Maybe not but if they had a real diverse group of holdings it looks a lot more like an asset manager than an investment club.