they are both paid... one is paid via money (display, textual) and the other is paid with time and/or money (organic listings)
they both have their pros and cons... If you master display and textual advertising it is evergreen... it will never die. it used to be classifed ads, magazine/newspaper display ads, direct mail, yellow page advertising... today in addition you have adwords, facebook, media buys, email buys, etc...
If you master this you can print money... the problem is you may not be able to master this.
Organic listings work for the time being because google needs you. Every year they need you less and less. Their goal is to make sure you cant produce a predictable roi from seo and every year they get closer and closer to that goal.
having said that there are benefits for the time being... for example being the 3rd organic listing garners a better ctr/traffic than the top paid position.
even being on the first page is better than alot of paid slots in terms of ctr/traffic.
In 3 months you can own an entire niche with seo with hundreds of kw's (not all #1 postions but pulling a healthy amount of traffic)...
Seo isnt a rifle shot business anymore... it's a shotgun approach.
The reason why display and contextual advertisers hate "seo'ers" is because most seo'ers are in fact retarded.
text/display advertisers focus on monetizing... seoer's focus on getting to the first page of a kw or a certain term, etc... what is their favored monetization? they dont know crap about monetizing so their vehicle of choice is adsense or some silly clickbank product. In general 90% of their traffic is wasted.
SEO is a catch 22... because you can set up killer monetization paths only to have google one day kill your traffic.
So the only way ive figured out how to properly "scale" a project like you would in display/text in seo is to sell the damn site. if you 3 months earnings you can get 12 times your monthly earnings.
if you have 12 month earnings you can get 3 times your yearly earnings.
I wouldnt touch seo today without such an exit strategy. 3 months is my tolerance. with google getting closer and close to killing seo, negative seo with pussies reporting your sites... a site that earns for 3 months is my limit for exposure.
the opportunity now is geotargeting but that too will soon die.
If you can master text/display advertising you are better off with that. The biggest mistake i see are people finding a winning campaign or a few and then living off of that until they die only to run around trying to start again. testing campaigns and launching campaigns should be a regular and consistent activity.
You want to eventually graduate into controlling your own offers.