heroin (or similar narcotics)?
I am an instrument of fear and propaganda,
Anti-drug campaigns often emphasize the adverse effects of drugs to scare teenagers away from them
I am bringer of ill news.
If you die of overdose, your family will have bad news
But if you see me, you may laugh,
You may be very happy when you are high and you see more drugs
I can distract you on a bad day.
You can be distracted by getting high
The world is glued to me,
Addicts are glued to drugs. Dealers may also be dependent on them (financially)
Loving but one part of me.
Love the high, but not the adverse effects
You complain of the cost of me,
Last time I checked, heroin is quite expensive
And can't use me unless you have, well,
Can't use drugs if you don't have drugs. Or if this is a continuation of the previous sentence, then can't use drugs if you don't have money
I would love to tell you, but then, of course, I'd have to kill you.
To understand the high you will have to try it, but each time you take it you decrease your life expectancy