It definitely is with a tapered cable. The only question is if it could be done practically and if it would actually be worth the hassle. The self support lengt

It definitely is with a tapered cable. The only question is if it could be done practically and if it would actually be worth the hassle. The self support length is for a cylinder of the material, with a cone there isn't a limit to the maximum self support length as the base just gets as wide as necessary to support the rest of it. But with graphene it's close enough that just a 10 to 1 difference in the cross-sectional area between the top of the cable and the bottom would be structurally sufficient. Since the area scales with the square of the radius a 10 to 1 difference is only sqrt(10) larger in diameter between the top and the bottom.