TL;DR: it's better for the earth, better for the body, better for the animals, and not really much of a loss in terms of what flavors you can have, as imitation meats abound.
1. better for the environment. Growing meat takes a LOT of land and a LOT of water, because you have to grow a LOT of plants to feed the animals. Here's an image for comparison: https://eluxemagazine.com/wp-content/uploads/2015/10/meat-land-use.jpg
another thing is, cows fart. A lot. And those farts are made of methane, a greenhouse gas. So not only does farming meat cause deforestation and water waste, it also causes climate change in an even more direct way.
2. have you seen what factory farms are like? The cows live packed together with no room at all, and they are fed growth hormones to make them big faster. Then, they are killed, though some don't die and are butchered alive. Now tell me, how can you justify that? Because they're dumb? Let's say some aliens came to earth, and they were much, much smarter than us puny humans. Would that justify them farming us for meat? No, of course not! Simply because an animal is "below" you doesn't justify farming them for meat.
3. science has shown that it's also unhealthy for the human body to eat meat. People say that you have to eat meat to get all your nutrition, but that's not true. Protein can be gained from beans, mushrooms, and many other foods. Plus, if you like the taste of meat, there is plenty of imitation meat that tastes delicious, for example the hyperrealistic Impossible "meats", the Beyond "meats", Tofurky (which for some reason has a bad reputation but tastes great), and the humble tofu, whose firm variety can be used with yellow curry to make delicious scrambled tofu (doesn't exactly taste like eggs, but I've heard adding black salt can solve that), etc. and there are plenty of youtube channels out there that teach delicious vegan cooking of all kinds, including sweetpotatosoul and itdoesn'ttastelikechicken, among others.
4. if you think about it, eating meat is kinda gross, as you're eating the muscles and fat (and some people eat other parts too) of an animal's carcass. Ew.
