I dont know how you've come to believe that, but it is not even remotely true. Cows eat parts that humans do not, but what they're fed is not a product that'd otherwise be wasted. Deforestation to feed livestock including cows is a real thing and soy is a big part of that. Feel free to eat as much meat as you want, but the least you can do is not share false information.

When someone mentions soy, we often think about foods such as tofu, soy milk, tempeh, or edamame beans. This feeds into the argument that meat and dairy substitutes – such as switching from meat to high-protein tofu or from dairy to soy milk – is in fact worse for the environment. But, only a small percentage of global soy is used for these products. More than three-quarters (77%) of soy is used as feed for livestock.

https://ourworldindata.org/drivers-of-deforestation