Too Long; Didn't Read
For a lot of developers, the last thing they want to do after being at work all day is write more code. Doing personal projects will make you a better developer and here are a few ways how. You get to experiment without judgement and learn how to handle more of the application life-cycle. This is your time to learn something that you actually care about and work on something sounds fun to you. It doesn't matter if it's pretty or not because it's just you playing around. By playing with code and having fun doing it, you're still learning.