Well ..... it doesn't. If it worked, fully, there wouldn't be any piracy, would there?
Is there a form of copy protection in existence that hasn't been, or won't be broken?
It's a balance. The calculation games companies make is that they can prevent some people pirating, and that of those, some will buy. More especially, the calculation is that they can do this in the critical golden days after release. These days, whether a game is a commercial success or not often depends on sales in those critical first few days and weeks. If they can prevent it being pirated for that first few weeks, then copy protection has done what it needed to do, and anything after that is a bonus.
So in that sense, it works if it prevents mass piracy for a few weeks, because that's when the main surge of sales will be, and most critically of all, when the most
profitable sales will be, due to those that must have (and usually brag about) the latest game on the day of release, and will pay top dollar (or even a premium) to do so. If you lose them (and that's why pirate releases either in the hours after release, or even pre-release are so damaging commercially), it can make a couple of years of development work a commercial failure.
Those companies also
know that it will cost them sales from people like me. They don't much like that, but it's a price they'll accept.
So whether DRM works or not depends on your criteria. From the company point of view, it works if it holds off large scale piracy for a few weeks.
But for me, it works if it stops piracy
without mucking me about too much. If it means I have to go begging for activation codes because I've reinstalled Windows too many times, or moved from PC to PC too many times, or I'm coming back to an old game after a long (maybe years long) break, then it doesn't work. If I have to have an internet connection to get a game I bought to play, then it doesn't work. If I risk that game purchase becoming totally valueless because it relies on online activation from a company that may not exist in the future, then it doesn't work. For me.
Also, for me, if whatever the DRM is starts screwing around with low-level aspects of my PC without even telling me, let alone asking permission, then it's a total and utter non-starter for me. And some forms of DRM
do.
If the use of DRM was openly declared, so I know I'm getting it before I buy, and what the implication are before I buy, then I'll buy based on what I find acceptable. But if that means I have to spend ages researching (and remembering) what a myriad of different DRM techniques do and don't do, complicated by it changing as revisions change, and as companies decide to change exactly how they implement it and what the criteria are, then I can't browse, pick a game I fancy and buy because I have no practical way of knowing quite what I'm buying.
While that situation exists, and frankly I don't expect it to change, I won't be buying
any more PC games.
The good news? It's saving me a fortune, both on game purchases and on buying £50 graphics boards, not £350 ones. I guess I should thank DRM, because it sorta funded my next PC replacement.