Scuba diving is an expensive hobby - It can be, but then so can many other hobbies. Also depending on where you are based, and where you take holidays, it can actually work out cheaper than many other technical/equipment intensive pass times. The equipment itself can get pricey, but at entry level you don't need your own full set, and as long as you buy the best you can afford every time you make a new purchase, you will not be disappointed
It's risky - there are elements of risk yes. After all, the underwater world is not one which naturally sustains human life. But that is why there are so many safety measures, back up/redundancy systems, buddy checks and emergency drills. To eliminate as much of that risk as possible. Statistics tend to back up this view, with much fewer reported accidents in diving than in some other sports that are considered 'safer'.
It's complicated - children as young as 10 can take their open water. That should tell you all you need to know about how complicated it is!
It's for people who don't have a day job - Not true - several divers only dive on holidays/weekends
It's for men - I don't know the stats exactly, but I guess its true that on the whole there are more male divers and dive pros out there - but also a lot of women. So no, its not a male sport, and hasn't been for a couple of decades!
It takes forever to get certified - in some holiday destinations courses can take as little as a few days
It allows for a very little margin of error (make one mistake, and you're toast) - I think there is lots of margin for error. As long as you dive safely, conservatively, within the scope of your training and abide by all cpu/table limits
It requires you to be good at swimming - 200m swim and 10 min float is all thats required for OW cert. Admittedly most instructors would like a bit more competence than this, but technically not required by standards
It increases your risk of being attacked by sharks - I think surfing increases it more. We've done many dives with sharks over the years - including bull sharks. And none of them seem to have been tempted by a nibble
It damages your ears over time - it shouldn't if you are equalising early and often on descent, ascending slowly, and avoiding diving whilst sick/congested