> how the heck is this 100lb weight a 100lb weight?
Because the scale that reads 100 lb is pushing up on the weight. The same would be true if the scale was inside a rocket accelerating at 1 g in deep space, far from all gravitating bodies. (This is called the equivalence principle.) In other words, the 100 lb of force you are calling "weight" is not a "force of gravity"; there is no such thing. It's a non-gravitational force exerted by the scale on the weight.
Because the scale that reads 100 lb is pushing up on the weight. The same would be true if the scale was inside a rocket accelerating at 1 g in deep space, far from all gravitating bodies. (This is called the equivalence principle.) In other words, the 100 lb of force you are calling "weight" is not a "force of gravity"; there is no such thing. It's a non-gravitational force exerted by the scale on the weight.