You ask why it makes sense to legalize pot?

You aren't creating a "new" problem! The problem already exists. People are smoking pot obtained illegally. Ignoring the problem doesn't make it go away.

Legalizing pot may actually decrease the amount available on the streets today to underage children. It will allow the government to have some control over the situation. It will allow Law Enforcement to concentrate their efforts on more serious offenders than pot users.

It is happening anyway, why ignore it?