The time it takes to learn how to draw people really depends on how you learn and how much you put into it. Many places will try and sell you books and guides which show you example drawing and step by step guides. This is all very fine and well, but it can take a long time and limit your drawing ability.
The best way to learn is through easy to follow video instructional videos. And while usually these are quite expensive there is one website which offers free video drawing guides. Enjoy!
Drawing call really open up a lot of doors. If nothing else, it can be incredibly fun and this is by the best and easiest way to learn. Don't believe people who say you can't learn to draw, you can only be born with it. I could barely manage stick figures but after a few videos and a few nights practice I was on the way! It's easier than you'd think to learn how to draw people.