Can't really say the "why" occurred to an 8 y.o. me making my own characters and drawing them was fun. More stories came into life, more characters, at some point I found myself drawing characters for a few more stories from another people, my friends. They loved what I drew for them and we enjoyed the process of creation together, it was a lovely time. I was never a great writer, but I enjoyed being hugely involved with creating whole universes together.
But even though I loved to draw my characters and read manga, I was always afraid of doing comics. I wouldn't start doing them if it wasn't for Bakuman. It inspired the hell out of me, "you always wanted to do it, you can do it", it told me