If you're not worrying about your paying customers, you're already a dead company. And while you're worrying about your non-paying customers, you're actually destroying your sales by driving away those paying customers by implementing poor implementations of DRM.
Of course game developers worry about their paying customers. Otherwise, why investing millions of dollars creating a game? They are certainly not investing half of these money into creating DRM, right?
The problem is, when you see the money, time you invested into making the game, does not give you meaningful returns, where probably half of your sales are going to pirates, it's very hard to keep going this way.
There are many ways to make DRM work better. For example, DRM on consoles seems to be fine. The problem is, PC is an open system. It's very difficult to make a working DRM platform on an open system. Take media check as an example. In early days, media checks focus on making the media difficult to copy. There were many strange protection systems. The reason is that CD was not designed with this in mind. But this is actually an easy problem! Even the ancient Playstation won't work with a copied CD without a mod chip. But on a PC, you have to worry about many different possible CD-ROMs out there. It's not simple.
Now with DVD it's actually much harder to copy the media since DVD has "built-in" anti-copy system. But now the problem is not about copying physical media anymore. You don't need to copy the DVD when you can simply emulate it (actually this is an old trick, it's there when games were distributed on floppy discs). So now DRM systems like SecuROM or Starforce have to defeat these emulators. Unfortunately, CD/DVD emulators have legitimate uses, so this practice can cause serious problems.
The ill-fated trusted computing was one possible way to solve this problem. Basically it created a closed system inside an open system, which makes a working DRM platform possible. Personally I think the cost is reasonable. Unfortunately, fear mongering articles on the internet were too successful, so there's still no satisfactory way for solving this problem.
A proper DRM system can also be beneficial. For example, currently many stores refuse to refund for returned softwares, because they can be "copied." It's not completely illegitimate though. However, with a working DRM system, where it's very difficult to "copy" a game, it would be much easier to push them to accept returning a game for a refund.