Everyone has a Limbic system, which responds to pleasure in order to reinforce behaviors, yes. Even eating or drinking water releases some amount of Dopamine so that you keep doing it. However, the Limbic simply was not designed to deal with the obscene amount of Dopamine and other analogues released by synthetic drugs. It literally gets overwhelmed, confused, and believes that it needs the drugs to survive. The Beast is this new, perverted survival drive.
I can see how some people try and re-created that rush with other activities, but they are never going to get to the same kick out of it that they would with drugs. The amount of Dopamine released by eating cake simply can't approach the amounts released by the ingestion of alcohol, or other, more potent drugs. I drink a lot of coffee when I feel down, and it seems to help in the short term, but it is nowhere near as strong as say, whiskey.