Yea, we see somewhere between 50-75% flake. You have to invite a LOT of people to end up with a few showing up. Without a way to post the Sankey diagram:

Out of 30 people invited to a typical house party, I'd say maybe 10 respond that they'll come. Out of those 10, 3-5 will actually come. Out of the 20 people that didn't reply, maybe 2-3 of those will show up unannounced. So you need to invite at about a 3:1 ratio.