There's a legitimate non-money-grabbing reason for having rarer cards: limited formats. MtG is divided into "constructed" formats where you build your deck in a

There's a legitimate non-money-grabbing reason for having rarer cards: limited formats. MtG is divided into "constructed" formats where you build your deck in advance from any legal cards you can obtain, and "limited" formats where you open sealed packs of cards and build your deck on the fly. It doesn't matter if mythic rare cards are unsuitable for limited because they're unlikely to show up there, so it gives the designers more freedom. See https://en.wikipedia.org/wiki/Magic:_The_Gathering_formats https://en.wikipedia.org/wiki/Magic:_The_Gathering_formats But I think in practice it's mostly about the money.