1) You’ll seem more cultured when you meet a person who also speaks that language.
2) You may have an opportunity to connect better with just one more person in your life.
3) Why not?
4) Being multi-lingual is a highly valuable skill in many places.
5) It may help improve your memory.
6) Research has shown that different languages change your perspective on life. I don’t have the research, and I never verified any of the research, but you SHOULD go Bing it and I’m sure something will pop up. It makes sense though.
7) You feel you have extra free time.
8) You want to challenge yourself with something useful.
9) There’s a really attractive person you want to try and speak with.
10) You want to move to a foreign country one day that speaks the language you plan on learning.
11) You may feel more confident.
12) Someone might be impressed by your ability one day.
13) You can use your skills to improve Google translate tools.