So when I worked for the cable company straight out of uni and we would look up famous local people to see what packages they subscribed to, we should have all been fired? I guess technically, but that's pretty draconian. Are you also no mercy, hard on crime, 1-strike and you're out person, or more progressive in that area?
You answered your own question. Seems you're having trouble taking responsibility for the fact that you acted unprofessionally by lashing out with presumptive attacks on my beliefs, which are incorrect. The culture of that workplace is a mitigating factor for the lower ranked staff, conversely it is a compounding factor for the senior staff that failed to put an end to it and discipline those involved.
Should you have been fired? Depends on how much you abused your privilege and what you did with that information. Your comparison to 1 strike laws and greater crime is pretty rich given the information you improperly accessed could be used to blackmail others, or whatever. It's important to treat such information with the utmost respect. Your cavalier attitude and inability to accept responsibility in this regard may be very common within the tech industry, but such attitudes are also why there is a growing movement to; take data out of the hands of companies, and to harshly punish companies who fail to protect the data on one hand while vacuuming up as much as possible with the other.
I'm honestly somewhat mystified at the lack of personal ethics where you could justify in your own mind that you shouldn't be fired for this sort of breach of trust. But I shouldn't be I suppose...I've seen all sorts of appalling behavior excused with 'gee, it's not like I killed anyone...'.
This kind of thing has to involve cultural change where people internalize on a deep level that looking celebs up is a big no-no. You have to judge people by contemporary standards, and for this reason I think you do not deserve as much punishment as future offenders.