A while back, a friend asked me what capoeira was and what I got out of it. I gave him my sentiments, but I felt wary about defining it. There's a multiplicity of definitions in capoeira and a real sense that one shouldn't speak for other capoeristas or capoeira as a whole. Yet if I'm the only capoerista my friend knows, in a sense I am all of capoeira to him.
Perhaps a great mestre would have no hesitation, but I'm a total novice, after all. It's not my place to say why anyone should or shouldn't do capoeira, unless their motivation is immoral (e.g., they are looking for victims for their serial killing spree) or certain to lead to disappointment (e.g., they think it will make them ten inches taller and regrow their lost hair). Then again, I'd say the same things about reasons for doing Tai Chi or playing the zither, and I know nothing about either one.
Also, the reasons people come to capoeira are not necessarily the reasons they stick with it. Maybe they think the acrobatics look cool, maybe a father figure teaches it, maybe they want to impress girls. They might even get what they are seeking; capoeira probably impresses some ladies. (To my sisters of the heterosexual persuasion: It doesn't seem to work the other way, alas.) But you quickly figure out there are faster ways to most of those ends. If you don't develop some other motivation, you won't stick with it long.
A few of the reasons I commonly hear is that capoeira gives you community (it does, but so does joining a WoW guild); that it makes you fit (it does, but so does Zumba); that it's Brazilian (it is, but so is samba). In fact, samba and Brazilian jujitsu also meet all those criteria.
Some people like getting pretty cords; others like discovering they can do things they didn't think they could; others like the aggressive, competitive aspect; and others still like its similarity to dance. For others, its Brazilian/African roots are most important. My highly unscientific theory is that you can tell what it is practitioners value by looking at the other things they choose to do. If they don't do anything else for fun, well, they're probably a contra-mestre, at least!
So, if I hike, do yoga, and read a lot, you can reach your own conclusions about my purposes.