Polyethylene made from only 50 ethylene monomers:

If this looks like a lot, imagine a hundred monomers! A thousand! Hundreds of thousands!! Whew, that's big! And those would be typical sizes for real polymers. How many pages would a polymer that big fill up? But remember: atoms and molecules are really, really small. Even the biggest polymer ever made can't be seen with the naked eye or even optical microscopes.

Notice that the longer the chain gets, the smaller and less important the initiator looks, doesn't it? That's why we weren't too worried about him earlier.