From the Dow Corning website
"Did you know ... Outside of the petroleum industry, Dow Corning Corporation maintains the largest distillation operation in the world!"which is more proof that the organic chemical industry, including the polymer industry, are deeply indebted to the petroleum industry. Silicone is the second most common element in the earth's crust - obtaining the raw material is easy as going to a nearby sandpit. After a few reactions, distillation and more reactions, you have silicone polymers for $10/lb and more.
Compare this to organic chemicals whose raw material are obtained from the bottom of a well, in some cases the top of the well is several thousand feet beneath the ocean surface. Such wells cost millions to drill, and this is all just to get the raw material. Add in some reactions, multiple distillations and more reactions and you come up with the starting materials for organic chemistry which cost just a few bucks a pound. Just keep in mind that in most cases, the starting materials that we desire so much are waste products from the refinery which is pretty much interested in producing alkanes of very high purity [*]. Quite the contrast, huh?
[*] The purity of course, is focused not so much on separating heptane from octane, but in separating heptene from heptane, etc...