I know you're not going to answer this question, because no one ever does...but just how often are you called upon to defend yourself? How many of your friends have been the victim of a violent crime?
In other words, before questioning the suitability of a tool for a particular job, first make sure that's a job that you need to do.
Or as a corollary to Mary's excellent question... If you spend the next two decades training hard but never get into an altercation are you going to feel you wasted all those years? That's a lot of energy to devote to something you never use.
If so you might want to consider if there are other reasons why you might want to learn something like Aikido...
And don't get me wrong -- I think you *should* be able to defend yourself using Aikido. But I'd really suggest you should have many more reasons why you'd want to learn it in the first place...
And "yes", "just because" is also a valid reason... Which is my reason...