Its a niche product. No one wants MRAM right now, so the people who produce it can sell it for however much they want to.
Its not necessarily better than DDR3 RAM as RAM, and its significantly less dense than Flash RAM. The practical applications of MRAM are not quite as popular as once thought...
So... it remains a niche product, with a niche price.
Again, MRAM is a niche product. So is a crypto chip. If you want a crypto chip, they are already available with Flash RAM / Microcontroller combos. There's no need to use MRAM for that application, when Flash is already widespread and cheap.
Its not necessarily better than DDR3 RAM as RAM, and its significantly less dense than Flash RAM. The practical applications of MRAM are not quite as popular as once thought...
So... it remains a niche product, with a niche price.