This question already has an answer here:
In short, a coworker is working on short stories / novels during his down time at work. While I have looked at this question, I think it's different in that his writing is definitely for profit, not related to the job at hand (programming), and he is a hired consultant with what I imagine to be a substantial billing rate.
Under more typical circumstances I would never bring this up, as I believe everyone should be free to take moments throughout the day to let their mind relax. Additionally, our team is very comfortable and open, and I can't imagine someone being disciplined for taking a moment to read the news or pay a bill online.
It might be a case of sour grapes for me, as I'd like to work on personal projects myself, but don't mix them with work because I think it's unprofessional on top of being harmful to both me and my employer.
Should I mention my concerns to my manager, or keep them to myself and not stir the pot?
Edit: Not sure it's relevant at this point, but just wanted to add for those asking in comments & answers - he is consulting on contract from a company that my company is partnered with. He has been around working on various projects (and whatever requests he's assigned) for the better part of two years. This is common at our company (I believe some are pushing 5 to 10 years).