Each time a person goes through nicotine withdrawal, they have symptoms that make them uncomfortable (e.g., restless, irritable, and anxious). They decide to have a smoke/tobacco break. When they have a cigarette, or a dip of smokeless tobacco, the hit of nicotine quickly helps them feel better. Their withdrawal symptoms disappear and they feel calm, but over time, this cycle supports the idea that tobacco helps them deal with the physical symptoms of stress. This makes people believe that using tobacco is a good way to deal with stress, no matter what causes it.
Using tobacco actually causes stress in the body - nicotine makes the heart beat faster and blood pressure go up, which makes the heart work harder. When the heart works harder it needs more oxygen. But if a person is smoking, the carbon monoxide they're breathing in makes it harder for the body to absorb oxygen, and this causes extra stress.
There are other healthy things you can do to make yourself feel better!