This strikes me as faddish because knowing only matters as long as you care. The moment that you don't care, knowing doesn't matter.
For example, let's take running. Your little electronic devices can tell you loads about your running, calories burned, totals, and all that stuff. Once you have all that data, what do you do with it? Really, what do you do? You accumulate it, but it doesn't actually provide you any useful information. Eventually, the day will come when your electronic thing has no power, so you make the decision to run anyway, and now your data is inaccurate. Maybe it breaks, and you run for a few weeks before you buy another one. Not only is your data inaccurate, but not having it on your doesn't affect your running at all.
Trackers don't help you get fit, they distract you from getting fit. Getting fit becomes data that proves that you're fit, which isn't fitness, it's just data. Eventually, most runners will realize that their own personal running goals are more important than the graphs on some program.
The devices are bought to solve people's fitness problem, but they don't solve the problem, they only measure it.
We've seen this happen before. Every fad goes through the must have stage, show it off, get tired of it, and discard it.
I also have no doubt that there will be some new measuring things that will prove useful. There will be niches and opportunities. I'm not a nay-sayer about everything, I'm just a nay-sayer about most of these things. In any place where the maintenance is a hassle and the rewards are marginal, human beings quickly figure out what's not necessary.
Most internet connected things? Not necessary. Most "smart" things? Not necessary.
Let's say you get a Bluetooth thermometer to track your kid being sick. Do you want to know the last think you'll think about while your kids is in your lap throwing up? That's right, you won't be pulling up your phone thinking, "I finally get to use this!" No, you'll be fumbling with it, have a crying kid, and say, "Fuck it." You'll look after your kid and manually remember the temperature. All you really need to know is, is the temperature going up or down, and is it over 100? Easy peasy. You don't need a device to do that for you.