Answer:
When a price increase does not result in proportionally lower quantity demanded it means that the price elasticity of demand is inelastic or ≤ |1| in absolute terms.
Nicotine is a drug, and drugs are addictive. That means that cigarette users are probably addicted to nicotine, and any increase in price will not affect the quantity sold, or its effect will be very low.
The most common example of inelastic goods are gasoline, electricity, and other utilities which have very low price elasticities. A price increase barely affects the quantity demanded.