Video: Do you need a monopod?
Well, do ya!?
In all seriousness, the need for a Monopod has diminished in recent years thanks to things like in-body image stabilisation, but that's not to say they don't still have their place, as the ever-knowledgeable David Bergman explains in this useful video.
For wildlife photographers there's benefits for resting your lens on a monopod to ease that tired, old back, and also for a few other types of photography like architecture and real estate where you need to get your camera into unusual positions on occasion they also have their place.
But its sports photography in particular that the humble monopod is most useful, especially as you're often using long lenses that are very sensitive to shudder.
So, before you ditch that monopod, watch David's useful video above.