Respecting the distance

I really should do some serious school work and stop procrastinating but this is interesting. I read an article about NYC Marathon about famous people who ran it this past Sunday.
I do not care about movie starts and similar. Instead I was looking at the results of former or current professional non-runner athletes. And it is weird. I start to think that maybe not everyone can ran a marathon. Or at least a decent one. Before I though that everyone can do it. If I was able to do it, everyone can, it is not that hard.

But look at the results:
Keir Dillon, professional snowboarder, 5:08:59
Justin Gimelstob, former professional tennis player, 4:09:58
Brad Ludden, professional kayaker, 4:16:19
Amelie Mauresmo, former professional tennis player, 3:40:20
Yannick Noah, former professional tennis player, 4:01:38
Amani Toomer, former New York giants wide receiver, 4:13:45

I know only Amelie Mauresmo and do not know any of those other athletes so I cannot tell how old they are or when they finished their careers.
But I would expect any professional athlete, who is/was among the best in the world, to be able to run a marathon well below 4 hours. Well, even below 3:30 should not be a problem for them, since 3:30 is not that great, right? They were/are paid to train and they train/ed, hard. I think that if they decided to runt he race they were actually training for it at least a bit. And even if they did not do a special hard-core marathon training, they should be have enough strength and endurance? So why are not they able to run a solid marathon time.

Interesting.