Your source is based on USDA data, which I assume is per capita US consumption. Meat and seafood consumption are quite different in other parts of the world.
If it's cheaper than the price of fish (which I think is the long term aim of Beyond Meat et. al.), you will definitely sell the poor and lower middle class. Meats and seafood are more expensive parts of a diet.
It's better for the environment (smaller carbon footprint), it's more ethical, and it's cheaper -- if the manufacturing of meatless and seafoodless substitutes can achieve this at scale.
Seafood consumption is far higher than meat-- good luck to these folks, it could be highly profitable.
Update:
Worldwide meat consumption (first graph): 317,000,000 tonnes.
Worldwide seafood consumption (later down): 154,850 kilotonnes, or 154,850,000 tonnes.
Seafood is roughly half of meat. That's still a large market.