Here is a quick idea of how GBs work:
Someone suggest a GB
We seek interested members (takes from few days to weeks sometimes, but it has been faster lately thanks to this dedicated site and our members cooperation)
Once the target of interested members is reached, we make a payment link for everyone to pay for his seat. (takes from 24-48 hours to close)
Once we close the payment link, we look for a volunteer to buy the product (this also takes time, sometimes 2 days, sometimes few weeks)