3) It demonstrates broadmindedness. Broadmindedness demonstrates cultural appreciation. Interests and hobbies make you look big and broad (not literally!)
4) It exposes you to many more contacts. Let’s stop hanging out with just bankers. The people in a gym class, a pottery show-case, a poetry reading – they also need you and your services. Surprisingly, they may open up a whole new market for you.
5) Life is too short to not have fun! Refer back to reason number 1. Don’t spend all your time in the office. Get out and explore your interests. Have fun doing something that may well open a door for you in the future in a way you never anticipated.