I could be totally off with this analogy, but this argument is similar to the thinking that overtook my mind a few months ago when I was doing a case study on whether or not Apple should release an eBook reader (complete coincidence).<p>I kept thinking to myself, "Why would anyone ever buy an eBook reader? Netbooks are becoming cheaper and cheaper (much cheaper than readers even then), smartphones are becoming better and better - and those are full-fledged computers."<p>To this day, I still don't completely know the answer....except what I do know is that a lot of people spend a lot of money on eBook readers.
Perhaps it's something along the lines of facebook chat - just because facebook has it, and ALL your facebook friends are on it doesn't mean people have switched over to it en masse. I still use and prefer many other chat programs - perhaps for stylistic, habitual, or illogical reasons - but significant reasons enough.<p>To foursquare - I say keep going. At the very least, competition is good, and at best, I think you have a good shot.