Well, based on ONS figures, it would appear the situation is stable, even with falling budgets (I am taking your word for it that they have been cut).
So, superficially, it would not seem unreasonable to say why spend more?
But, personally, bearing in mind we are talking about the consumption of illegal substances, I would possibly doubt the accuracy of the figures. I also have some personal experience of drug abuse, criminality and ensuring problems.
As I have already posted, it is my belief that the battle is unwinnable. That is an opinion, I am not an expert, are you?