It is a "psychological trick", especially when combined with other incentives like badges, leaderboards or rewards.
Keep in mind that many people struggle to get even a few thousand steps. Beyond that, it's a great status symbol, or at least it was, until the Apple Watch came out :-)
Also, the data can be interesting, both for researchers, and for yourself--if you're the kind of person who wonders e.g. if getting a lot of steps late in the evening rather than in the morning affects your sleep...
Keep in mind that many people struggle to get even a few thousand steps. Beyond that, it's a great status symbol, or at least it was, until the Apple Watch came out :-)
Also, the data can be interesting, both for researchers, and for yourself--if you're the kind of person who wonders e.g. if getting a lot of steps late in the evening rather than in the morning affects your sleep...