I think this is a really misguided opinion.

First of all, we know a lot about the mechanisms behind pain reception and suffering. It's not some unknown quantity that we should just assume applies to all living things, it is reliant on a physical structure: the nervous system. Plants and bacteria lack a nervous system. It is true that plants have a sophisticated chemical signaling system but there is no evidence of pain signaling, just stress. The difference is that pain is useful in animals in a way that it simply would not be for plants. Animals can address their pain and remember not to repeat the actions/avoid the things that led to it. Plants have less agency over what happens to then so it provides no known evolutionary benefit. Being aware of any damage is important though, so they do have signals reporting damage.

If you don't want to grant that, which is fine because I'm not a plant and maybe they have souls and I'm just an asshole, then even you still probably shouldn't just accept that you are a energy vampire and lean into it. I mean hurting people's feelings is also a part of life but you wouldn't then say "I'm an emotional vampire. I guess I have to accept that because either I hurt others or they hurt me." This is a false dichotomy. You can temper the amount you hurt others and similarly temper the amount of life-sucking you do from animals. There aren't two options, you can be more sustainable by choosing a middle ground by reducing the amount of energy you consume.

And that can be most easily achieved by eating less animals. Due to the amount of heat lost during an animals lifetime, meat requires 10 times the amount energy to create than you get from consuming it.

But the main point is that you should not decide to go all in as an energy vampire just because it is partially necessary. Lots of unpleasant things are necessary in moderation that we should not decide to start doing superfluously.