Marcus is a 19-year-old university student who has recently moved away from home to start a demanding engineering degree. He feels highly isolated and anxious about his new academic workload. To ease his transition, he spends evenings in his student flat's shared kitchen, where his flatmates regularly vape and use high-strength nicotine e-cigarettes. Marcus, whose father and older brother are both heavy cigarette smokers, has never used nicotine before. However, after trying it once with his flatmates, he found it significantly relieved his anxiety. Marcus now buys his own vaping devices and finds himself vaping constantly throughout the day, including during his lectures.

Using your knowledge of risk factors in the development of addiction, explain Marcus's escalating nicotine addiction.