I am really not that knowledgeable about this space, but I would imagine it's because A) there are a lot of subsidies for the meat industry, and B) there are a lot of economies of scale present in the meat industry that do not yet exist in alternative meat industries.

Of course, it makes sense that when introducing a new product like this to the market, it is potentially going to be more expensive than existing products. It seems like, in theory, one should be able to make it much cheaper just because producing meat by way of animals is just very wasteful from an energy perspective. However, I have no clue what is required to synthesize such compounds without the use of animals, so I don't know how far away we are from being able to do this.