You keep saying this but I think you're missing more than half the picture.
1) You're ignoring the manufacturing cost difference. Correct me if I'm wrong, but my understanding is that the theory is QDSC can be manufactured at extremely low cost via high-speed R2R printing making QDSC far less expensive to manufacture than Si solar cells.
2) Why do you assume it takes 1g of QD to replace 1g silicon? If it takes 1g QD to make a 60" TV, maybe it only takes 1g to make 1m^2 QDSC? How many g of Si does it take to make 1m^2 of Si solar cells?
3) How do you know that QDs for QDSC will cost the same as for display? Maybe they use less expensive component chemicals, are easier to make, or don't require as stringent specs as display? Maybe they cost a lot less than $100g?