Nobody's forcing any company to buy their chips from TSMC. They're free to go elsewhere, same as nVidia did when they went to Samsung for their last generation GPUs because they were not happy with how much TSMC wanted to charge them. Or they're welcome to go and try to get a better deal from Intel (fat chance).
If anyone is greedy in this equation it's Apple and not TSMC. If TSMC's prices are so unreasonable and exploitative then how is Apple still posting record profits every quarter?