It's still a niche market. Tourists use them because they are rare (so Segways are marketed as a tourist experience). This puts them in the realm of donkey rides and pedal boats as far as the tourist market is concerned.

Their practical use is limited to places where cheaper, simpler alternatives can't be used — this basically means places you wouldn't use a bicycle or electric scooter because of the collision risk or space constraints, like shopping malls. Even in large data centres and huge warehouses people would choose bicycles over Segways ­— a dedicated indoor bicycle is cheap and quite low maintenance.