Smoke if you want. A lot of people smoke because they enjoy it, or genuinely can’t kick the habit, or need it to cope with a variety of anxiety issues and more.
But please do not smoke in public places not designated for smoking. People have allergies, people have respiratory problems, the smell of the smoke could be a trigger to some people, and frankly it smells awful and clings to clothing and it is rude. It’s not just dangerous to you.
Designated smoking areas are there for a reason! Please use them, please crack a window, please do not smoke directly around other people in a non-designated place. If it’s your own home, your car, that’s fine – it’s your property, but please be considerate.