the problem is there are so many hacky, cold-calling SEOs that the majority of people you're likely to run into in SEO suck. when you really get into it (obviously biased) i think the combination of statistics, data mining, creative content and competitive analysis of your position in a perpetually changing market is a fascinating blend and you can learn as much as you want and take your skills and strategies in a ton of different directions.
it'd be nice if we could be completely transparent with analytics while iterating a search strategy for a large site, because the learning experience would be great whether you're a big-name, experienced SEO, looking to get further into SEO, or an anti-SEO hacker looking to just call us all out for being full of shit :) it'd be cool. too bad the economic reality of releasing complete analytics data to the entire internet makes this an impossible dream.
It's not easy getting links. More importantly, if you have a great product where everyone else has great products, the marginal benefit of having the best product with the most amount of authoritative links is huge, because the # of clicks that come from the top result over #2 is monumental. So even if you get thousands upon thousands of links, like those that rank for "cheap flights", it's the site that gets thousands and thousands +1 that will win the day, and make millions more on a long enough timeline.