here are some people that do...
See Meggie Run
I have followed Meggie's blog for years. Her husband ran Boston yesterday. They are both fine.
"If you are losing faith in human nature, go out and watch a marathon"
The People Who Watch Marathons
And finally, a college friend of mine's facebook status this morning:
"My morning routine: get the coffee on, check email and social media, skim news headlines (read an article or two), go over the agenda for the day. Just one seminar this afternoon. -- A morning like any other here in Boston, except not really at all."
He lives on Boylston Street.