One question we regularly hear at Datalogics would be, "How secure is Adobe DRM?" or "Can Adobe DRM be bypassed?"
The short answer is yes, Adobe DRM can be bypassed. However, this is also true for every other ebook DRM that I'm aware of at time of writing, including those provided by Amazon, Apple, and Denuvo. The nature of DRM is that a DRM implementation is never finished. The security providers are in a constant arms race with piracy groups and distributors. For example, Denuvo, provider of one of the industry standard DRM solutions for video games, admitted back in 2017 that their DRM would only protect a game for a limited period of time. It would eventually be cracked.
This isn't because Denuvo's video game / movie DRM is bad. Rather, this is the nature of the DRM arms race.
For various reasons, the efforts of companies in the eBook world is much slower paced. This is why there are methods to crack the DRM of all three major eBook DRM DRM solutions, including Adobe DRM, Amazon’s Kindle DRM, and Apple FairPlay DRM. Despite having the weight of companies like Adobe, Amazon, and Apple behind these solutions, the DRM can't protect forever, and the three companies don't push out updates at the speed done for movies, video games, and other online content.
That’s not to say that DRM is entirely useless. The DRM does raise the floor of bypassing protected content enough that many users simply won’t go looking for the bypass method. Other people will read up on how to do it, but won’t bother to actually find cracked content / bypass methods. Some will, some won’t. In my experience, consumers generally follow the path of least resistance, so if your content is easy to purchase and access, they’ll go ahead and do that and the DRM keeps them honest. Video game users are generally technically competent enough to find and use cracked versions of games, but sales are up anyway. The recently released video game Elden Ring, easily found on piracy sites, is still selling well. Steam's Gabe Newell once said "Piracy is a service problem." A similar article from Forbes says the same thing.
But it seems that raising this floor does have value, despite Denuvo admitting that their protection is temporary at best. Plenty of video games still launch with Denuvo DRM, many of which launch on Steam.
I understand that this isn’t what people really want to hear when discussing DRM, but it’s the reality of things. There hasn’t been nearly as much industry money going into eBook DRM solutions as there has been for video game and movie DRM solutions, so eBook DRM effectiveness lags behind. Even with movie and game DRM though, it’s at best temporary protection, though the industries still find value in keeping honest people honest. In the eBook realm, we at least have the advantage that many users aren't technically inclined to look for and then bypass DRM. There are plenty of cases where people simply try to copy the protected file, find it doesn't work, and then move on.
So as far as preventing users from going around DRM protections, with Adobe DRM the best that you can do is use the hardened option. And while I’m not familiar with the implementation details of Amazon’s or Apple’s solutions, I assume that their advice is similar. But there’s no way for you, me, or any of these companies to prevent someone from using a DRM crack once it’s widespread. Ultimately, once DRM is cracked it exists to “keep honest people honest.”