Keeping track of what you're drinking, how much you're drinking and how many calories your drinking is what this solves. It clearly isn't useful to you but it's automating a task that some people don't want to do manually. Why do you need a pedometer when you can count steps?
We can certainly argue the usefulness of this device for the average joe or how small their market may be but arguing that it doesn't solve any problems is silly.
If you're trying to lose weight, it's easier to just drink water. Then you know what your drinking, and how many calories it has (none!).
If you're trying to limit caffeine, you don't need a fucking sensor cup to tell you how many cups of coffee you had. Because most people can count the number of cups they've had on their fingers. Counting on your fingers is a lot easier than lugging a $99 dollar cup everywhere you go.
And that's pretty much the only reasons you'd need to watch what you drink. Lets cut the shit. This product is for people interested in "quantified self." People who think they can derive useful insights from looking at 3 years worth of their own toenail clippings. Hey, different strokes for different folks, but I doubt you can learn something from measuring your drinking that you didn't already know (Oh hey, I drink more wine when I'm sad... and soda makes me gain weight! I'm so glad I obsessively poured all my drinks into a $99 electronic cup).
We can certainly argue the usefulness of this device for the average joe or how small their market may be but arguing that it doesn't solve any problems is silly.