...As far as I'm concerned, addiction is the only reason for the existence of OxyContin.
		
		
	 
Continuing the metaphor...
For healthcare workers in US who were in clinical practice after about 1993-1994, we were told that we were undertreating pain.  Suddenly out of nowhere, we were told that pain was subjective, we were undertreating patients for pain and that patients who were in pain had low risk of addiction.  Pain clinics popped up overnight.  Physicians started changing their specialty to "pain management" (prior to this pain management was considered to be a subspecialty of anesthesiology).
We now know that the pharmaceutical companies had been donating money to hospitals, creating commercials and "education to promote their product and giving "grants" to doctors who prescribed the medication.  And there were internal documents from Purdue that indicated that they knew that their medications were creating addicts, and in some cases, killing people.  They mounted a disinformation campaign to convince the public that their drugs weren't addictive and the reports of deaths were exaggerated.
Around the same time, the gun industry created a new markets by convincing the public that violent crime was increasing (when it had been declining since 1994- around the time the assault weapons ban was passed, coincidentally).  Local and national news reported carjackings, home invasions, etc to convince the public that they were at risk.
The gun industry co-opted organizations like the NRA to make donations to politicians who would pass laws deregulating the gun industry.   At the same time, the industry started aggressive ad campaigns to market weapons created for war to become recreational devices, much like cars were marketed to men in the 1950s and 1960s.
Create new markets for product.  Run marketing efforts to convince the public there's a big problem.  Convince everyone that your product is needed and is the solution to a problem.  Flood the market with money to those who will promote/prescribe/write legislation.  When it become apparent that your product is creating the problem, create disinformation to convince everyone that you're still the solution, not the problem.
	
		
	
	
		
		
			I truly don't understand how or why people would become addicted to them
		
		
	 
The original market for Oxycontin was narrow, much like the market for assault weapons was on the battlefield.   The idea behind Oxycontin was good- that instead of chasing pain with pain medications every 4-6 hours, there would be one pill and it would be time-released and keep the pain under control.  
The market was there- particularly in oncology, HIV and terminal illnesses that had severe pain in their final days.  These were also places where addiction wasn't as much of a concern.   When you look at what the drug was designed to replace- stuff like 
Brompton's Solution- it seemed like a good idea.
But just like you don't need an AR-15 to kill a deer or to protect your home, you don't need a time-released oxycodone megadose to control post-operative pain that is temporary and will respond to less-addictive drugs.