Not just that. I'm not an expert, but from what I read, some DRMs will encrypt assets and critical game logic and let them be decrypted in real time on a virtual machine so that they aren't directly extractable from memory.
Once is in memory, encrypted or not, it can be extracted, inspected and replaced (which is what a launcher crack style does).
Yes, but figuring this out can still take a long time. Splinter Cell: Chaos Theory survived for over 400 days before being cracked.