The likelihood that someone will become addicted to a substance is actually much more affected by the route of administration than the substance itself. Addiction primarily happens as a result of people linking an action (e.g. taking a drug) with a reward, and the less time there is in between taking the drug and it taking effect, the more powerful that connection.

In terms of addictive potential for any given drug:

smoking > injecting > snorting > eating > topical

If you were to actually compare drinking crack with drinking coffee, the addictiveness of both would be identical.