This thread is somewhat weird. It's full of people saying "Of course Switch owners need to buy an additional console, otherwise they'd miss too many games", when the time scale alone (Xbox One and PS4 being on the market a lot longer than Switch) means that this is likely mostly not about Switch owners buying an additional console, but about people who already own Xbox or PS4 buying a Switch. It's an important distinctions, because it changes the narrative from "Switch owners buying another console because they'd miss out on too much stuff" to "Switch offers appealing functionality and games to people who already own other consoles".
I consider the question whether people buy an additional hardware because the hardware they own doesn't offer enough games actually to be rather uninteresting, I think the general observation that Switch is apparently very appealing to people who already own other current consoles to be a lot more interesting. Likely also indicates (yet again) that the Switch audience is mostly older instead of leaning heavy towards a younger audience (which I don't think surprises anyone, considering both the price of Switch and the all age appeal of Nintendo's brands, which titles like Pokemon Go have shown quite impressively).