Very much so. Fixing software so that they correctly recognized my preferred serial number of #12345 was valid. Using soft-ice to register itself was always a deeply ironic.

But to be honest I started before then, on the ZX Spectrum. First of all it was patching games to get infinite lives, or time. But later it became necessary to patch the loaders before you could even access the game-code - speedlock, bleeplock, etc.