It isn't that simple though: if you're addicted to alcohol, you are often able to find suitable alternatives that are cheaper, which unfortunately fuels the habit.
You can't afford to drink expensive spirits, so you get onto drinking crap. Cocaine on the other hand, like many drugs, is an expensive habit that remains expensive.
A £30 bag is a £30 bag and when people become addicted it can quite quickly spiral into huge costs, often with significant debts, because it doesn't get cheaper.
So then what? This is why people who are on the coke or want to score are forced into other forms of criminal behaviour.
And its the same with drinking mate, once you run out of money and ale, you need to find more.