I'd overlooked this post and I believe I have an answer.
Hasbro must have managed to negotiate a deal with the company that is producing the masks. Hasbro has a policy of taking an up-front payment for the rights to use their intellectual property. So, a part of the sale price of each mask includes a payment to Hasbro for this license right.
All things considered, if this is the case, Hasbro is going very fairly on their standard cut of the pie from third party companies.