Good photographers try to be prepared for almost any contingency. Unfortunately, if you tried to carry everything you’d need to meet every contingency in the field, you’d have to pack like a Bedouin trader. Many times that simply isn’t possible.
So the seasoned photographer learns to be resourceful. In all but the most extreme lighting situations a monopod can substitute nicely for a tripod and is a lot easier to carry.
With practice you’ll be able to hold a monopod nearly as stable as a tripod.