This is a huge oversimplification but my recollection is, there is a design arm of the IKEA structure which is a non-profit. They create and own all of the designs and IP related to products, which a different IKEA subsidiary then licenses and pays royalties on, essentially negating much/all of the margin of the finished good.

it's not a charity, it's a ultimately held by a pair of Liechtenstein and Dutch foundations, with an elaborate sea of holding companies underneath: https://en.wikipedia.org/wiki/IKEA#Corporate_structure