You must have weird ears my friend
I could say the same. But lets not insult each other and just talk about the design.
How is a hard plastic slippery surface going to create a better seal with the ear canal than a properly sized rubber seal that most reasonable earbuds have? Whether Apple's fall out or not, the fact remains that they are not sealed into place. And no two ear canals are the same, so the hard plastic has no ability to flex to fit. The electronics design might be the best the world has seen, but the way they are mating to the ear is poorly designed and its pure luck if you have an ear canal that happens to have a shape that will come close to sealing with it. This is why most high end earbuds come with several different sets of rubber seals to allow the buyer to get a more custom fit.
So essentially we are back to "you are holding it wrong" if it doesn't work... except in this case its "your ear is shaped wrong" so its not Apple's fault it doesn't work for me. Maybe Apple's plan is to sell prosthetic ears that are designed to fit their ear buds so Apple fans everywhere can really go all in.