Dyneema is so strong because of the way that it’s created, it’s not a natural fiber like wool or cotton. It's made in a lab by taking ultra-high-molecular-weight polyethylene (UHMWPE) and sandwiching it between two sheets of polyester film.
This method makes it way stronger than traditional cotton fibres. The lightweight and durability of Dyneema fabric allow manufacturers to make textile gear with previously unheard-of strength-to-weight ratios.