DRM is supposed to protect your game, but it doesn't - It's a delaying tactic, nothing more. I also don't really consider 2 weeks a success, not really.So then it did work, it worked for two weeks. And during those two weeks by your own admission there was a noticible drop.
How can you possibly conclude that copy protection didn't work?
Second, this particular DRM took weeks and weeks to implement. As I said before, you have to weigh the cost of implementation, to how much you'll get back. This was on a AAA F1 game for EA, so the returns could be deemed to be worth "trying", especially as the returns on a PSX game would outweigh the cost of having a senior dev implement some kind of security. Also, this had some "physical" security that we could detect. The disc itself was written in a special way, and when pirates copied it, it wasn't there anymore. You can't do that on normal PC games, about all you can do is "sign" the EXE. This is a good first step, but make no mistake, it's only a first step.
Third, the tools available to crack PSX games at the time were virtually non-existent. It was very hard. But PC games have to cope with some amazing tools, making it very easy to crack the game.
As I said above, it's all down to how much you think you can delay them, vs the cost of you doing so. You can never "protect" your game - ever (short of a server based game), you can only delay. If you can afford a few months dedicated to DRM, knowing that it'll ultimately fail within a week - then fine. In fact, I'll even give you some tips on the bests ways to confuse them.
DRM tips
1) Don't just test and fail. These are incredibly simple to discover and remove.
2) On PC buy a code signing certificate. This lets you know that the EXE has been modified - watch out for anti-virus programs, they can lock your EXE when your trying to check it.
3) Don't put protection code in a DLL, they'll just alter that one file.
4) When you detect a "change" degrade the game - don't fail. Only fail about 5 or 10 min into the game. This makes testing a crack a nightmare. They might think it's all working, but it's not. This is how we held off the hackers for 2 weeks, they had to go into the game and play for a while.
5 Put hundreds of these checks and "flaws" into the game, making it really hard for them to find and spot them all.
6) You want the game to play well at the start, as this means hackers will effectively be putting round a free demo for you.
7) Remember that only a small fraction of those playing the crack will EVER buy your game.
8) weigh up the PR of having DRM free, to what you MIGHT get back in sales. Indie games traditionally won't sell massive numbers, so your weeks of effort might just cost you any sales.
9) PR again - Sometimes folk that play cracks think of them as extended demos, and really appreciate the effort devs go to help if things aren't working - even to those with cracks. You not only get good PR from it, but many will then buy it because you've been so cool over it.
10) Lastly.... if your game is just an installer, or has a key that isn't validated, then protecting the game is pointless - they'll just share the installer and the key.
I will say though.... If they game is easy to share (an installer or key), then DRM can help in stopping "cheats". Hackers usually won't be interested in hacking it as it's easy to copy, and that means cheats are on their own. If the game is signed and protected, then cheating is much harder. They'll end up trying to modify the game as it runs, and you can check that as well.