How does dependence make an addiction difficult to overcome?

Dependence leads an addict to rely on a drug just to be able to function.

Explanation:

Psychological dependence involves emotional-motivational withdrawal symptoms (e. g. anxiety, anhedonia, etc.) upon cessation of drug use.

This means that when an addict stops taking a drug they have become dependent on they encounter a wide variety of negative symptoms. This makes an addiction incredibly difficult to overcome because the addict is very likely to take more of the drug in order to stop the withdrawal symptoms. As usage continues, the addict needs to take higher dosages in order to combat the withdrawal symptoms. This leads to the danger of overdose and the strengthing of withdrawal symptoms as drug usage continues.