No. We evolved to eat & digest meat. You can't be healthy and be a vegan. It's one or the other.
I'm not vegan, but you're wrong. You can indeed be healthy and vegan, as long as you have a balanced diet including legumes, grains, seeds, nuts, and so on.
Obviously if you only eat salad, you're gonna develop some deficiencies sooner or later.
With a balanced vegan diet, the only thing you could potentially lack is vitamin B12, as it's mainly found in animal sources.
Vegetables actually contain some B12, but it comes from bacteria, so we lose it when we wash them.
Other deficiencies are extremely rare. Iron? Vitamin C doubles its absorption. Calcium? Most green vegetables have more calcium than dairy. And so on.
I studied nutrition and I could explain everything in detail, but it would take too long. I advise you to do your own research.
As for me, I've been a vegetarian (not vegan) for as long as I can remember, and I'm healthier than pretty much anyone I know. My blood tests are perfect.
I have no conditions and I don't take any drugs. I get maybe a mild cold every 3 or 4 years, and it goes away by itself in 2 or 3 days without drugs. That's all.
BTW, I think people can eat whatever they want. I don't care. I'm not the annoying guy trying to convince everyone to become a vegetarian or vegan.