Why are synthetic fibres stronger than natural fibres? Is it a magic?

Syntheic fibers are man-made polymers and are prepared by repeated joining of small unit known as monomer. This repeated joining of a monomer creates a bonding between the various monomeric units, thus giving it more strength and also, the strength of the synthetic fibers can altered by addition of certain substance or by preparing them with different methods, as per the requirement. This cannot be done with natural fibers. Therefore, synthetic fibers are more strong than natural fibers.