I am not thinking of dabblers; many people will do marathons after having barely trained. The goal for these people is just to finish.
I think 2:30 is achievable for a healthy, moderately talented man who is not merely dabbling: someone who is training correctly and has put in a few years of sustained, injury-free effort.
2:30 is still very much an amateur time. For example, I think that even though 2:15 or faster is professional-caliber it is still nowhere near being competitive.
Of course it's an amateur time: You're not going to win any serious marathons running a 2:30, and if you have no chance to win, you can't really be described as a "professional". But c'mon, 2:30 is an amazing time for an amateur. Obviously it's "achievable", since maybe a dozen "amateur" runners managed it in Boston this year, but it's well beyond "good", as you initially described it. It's well into the top 1% of amateur marathon runners.
This whole argument is slightly tangental, but I figured I needed to chime in ;) A 2:30 is a ridiculous time for an amateur. It'll easy put you in the top 0.5% of amateurs in the world. To put in this in perspective... a 2:30 marathon pace puts you at doing roughly 17m30s 5km's, 8 times in a row!
Haha, yes, I agree. 2:30 would probably be run at the pinnacle of one's amateur career -- a personal best rather than a typical time.
I do want to point out somewhat pedantically that it takes being in better-than-2:30 shape to run 2:30 on the Boston course, a notoriously slow course. There are runners who ran more slowly than 2:30 in Boston when they could have run 2:30 elsewhere.
I am not thinking of dabblers; many people will do marathons after having barely trained. The goal for these people is just to finish.
I think 2:30 is achievable for a healthy, moderately talented man who is not merely dabbling: someone who is training correctly and has put in a few years of sustained, injury-free effort.
2:30 is still very much an amateur time. For example, I think that even though 2:15 or faster is professional-caliber it is still nowhere near being competitive.