Would you steal bread to feed your starving family? The answer to this question is easy: yes, provided there were no other reasonable alternatives. While theft is wrong, letting your family starve to death is worse. Would you, however, sell marijuana to maintain your family's plush suburban lifestyle?
Although marijuana should be legal, it isn't. Botwin should not act in a hypothetical world in which marijuana is legalized, but the real one. In this real world, by growing and distributing marijuana she runs the risk of being arrested by the police or assaulted or murdered by rival drug dealers/gangs, leaving her fatherless children without either one of their parents.
And she doesn't just deal drugs to maintain her large suburban house, her pool, and her Hispanic maid; she does it because she enjoys the danger and excitement. She enjoys dealing with dangerous men, many of whom she's fucked (see the crooked DEA agent, crooked developer, Hispanic drug dealer, and a drug grower). She enjoys the cutesy, clueless MILF bullshit (for a show that enjoys poking fun at phoney bullshit, Nancy's dealings with gang members is the phoniest parts of the show).
Of course, running a drug business out of her home eventually causes her children to become part of the business, resulting in Silas becoming a drug dealer and grower himself, who gets beat up by a biker gang.
How does she solve the problem of the biker gang? Not by getting her hands directly dirty, but by getting some bad men to fix the problem--as she usually does--only to act shocked when they fuck things up. (Well, she did get her hands dirty when she burnt down the house; however, in general she gets other men to do bad things for her)
Finally, she's too preoccupied with her bullshit lifestyle to pay any attention to her youngest child. Her inattentiveness causes him to bring his father back to life, so that at least one of his parents talks to him.
