Paramedic here,worked in an area with lots of addicts for years: Most iv users don’t have start fresh. They are already addicted to Heroin,etc. and consume via smoking it, etc.

When the addiction gets bad enough that they switch to IV administration they are usually well embedded into the scene. Which consists of more than enough IV users which usually are happy to help/often they the new user has helped another user how to inject before they do it on themselves.

And tbf it’s not that hard when you just need to give a single injection with a rather small needle to someone who usually is on the younger side if the demographics, has thin skin, etc. But of course they miss (a lot), but that’s no biggie - most of them know how to aspirate first and they simply try it somewhere else then. And they get pretty good at it.

But of course nevertheless paravasals and abscesses are a huge problem, especially in more experienced IV drug users.