I appreciate where you are coming from. I am not saying that knowing how to fight is 100% useless re SD, but it is important for people to realize it is (IMHO) at best a very small part of an effective SD strategy.
The problem is the poster, like a lot of people, seems to think fighting is the best and only means of SD. It isn't.
In terms of general socio-economic status (i.e. living in a "good" area where you are less likely to get attacked) you have to ask is it better spend a lot of money on martial arts equipment/classes, or could that money be put to better use? For example, would it be better to go to night school and educate yourself, get a better job, get more money, and be able to afford to move in a few years? Or would that same money be better spent making your person/car/home more secure???
Additionally, lifestyle comes in to it. The most recent British Crime Survey compiled by an independent body for the UK Government found a person is over 50 times LESS likely to be a victim of assault if they don't frequent social drinking establishments (e.g. clubs, pubs). That's a hellvua risk reduction, isn't it? They found that almost 3 out of every 4 violent attacks in the UK involved alchol... you see where I am going with this?
I have met a lot of people who think martial arts are a golden hammer. They can go wherever they like, do whatever they want, get as drunk or as high as like, be as much of a jackass as they want because when it comes down to it, they can "kick ass". If they were more aware of themselves and why they do the things they do and how they treat other people, maybe they wouldn't be so inclined to learn how to "kick ass".
Another factor: The original poster goes to the gym. Who is to say that isn't as good a means of SD in terms of physical training? Here is a great thread about a person who fought off an criminal attack. She is a Crossfit member, not a martial artist (judging by the clip at least). She lifts weights, and does cardio work, including working on a punch bag. With all due respect, her punching technique isn't really clean, but it was enough to get her out of a bad situation:http://www.fightingarts.com/forums/ubbthreads.php?ubb=showflat&Number=422690#Post422690
She was able to defend herself by being in good condition, being strong and having a small amount of punching training. She was able to fend off an attacker without formal martial arts study (so it seems).
What about systems like Parkour...aren't they worth considering in terms of their self defense value? Is good parkour "better" as a means of self defense in an urban area than any martial art?
Hope, you indicate in your post that nothing is a guarantee regarding getting attacked. You could be the most cautious person in the world, and it still might happen. Quite right.
However, like I said, nothing is guaranteed. Knowing martial arts may be on no help whatsoever in a situation. On the contrary, it may lead to making a bad situation worse.
A person has to decide what they want to do with life and the best way to go about it. If people want to worry about getting attacked, or spend a lot of time and money learning how to fight while ignoring or barely studying (IMO) effective self defense measures, well, that is their choice.
Back to the main topic, the Crossfit thread showed you can do some traininig from gym. Look to see if a Tae Bo or boxercise class is in the gym. If you want to learn to fight, those may be good places to start.