I agree that fake meats aren't ideal healthwise, but let's face most individuals promoting a vegan diet are not promoting the fake meat products, that is the supermarkets and food producers, which let's face it have never had the consumer's health at the forefront of their minds.
A healthy vegan diet, which is perfectly cheap (I'm not including the fake products in this assessment), and very healthy is fine. Beans, nuts, pulses, veggies, fruits, cereals.... you can take B12 (which by the way is only more abundant in animal foods because it is added to their feed artificially) if you need to.
And as for all vegan milks supposedly being unhealthy, there are plenty of healthy vegan milks, you can make your own for pennies from oats and water or buy soy milk or whatever.... the Japanese have subsisted on soy milk for years and are some of the healthiest around.