This is NOT a scare tactic, it is a reality. While it is not true in ALL cases, it is true in MANY cases.
Many cracks, keygens, and pirated software contains malware. This malware may install itself transparently to the user, and once installed be nearly impossible detect by your security software (which likely won't initially detect it since malware is regenerated daily). Unless you wish to end up with a rootkit installed and your PC turned into a zombie machine, I strongly recommend all users stay away from cracks or keygens. Our software is mostly free anyway. Do not take this risk!
These are facts, but you don't have to take my word for it. Do a search yourself on the risk of downloading cracks, keygens, and pirated software. It is perhaps the largest vector through which malware gets introduced into a PC.