IMO Programming is much higher risk/higher reward than SEO.
You have huge potential to make serious $$$ through a start-up, SAAS, web or mobile app. But programming is difficult to learn, isn't "fun" for a lot of people, and the industry is quickly becoming worse and worse to work in. Look at how average salaries are dropping around first world countries compared to outsourced developers.
SEO, on the other hand, is arguably much easier to get into with almost zero start-up cost (low risk). Tons of great free resources out there using tools you likely already know (Facebook, Reddit, Twitter, Youtube etc). You can go from nothing to making a couple hundred $$$ in much less time than it takes for programming something.
But in the end, whoever is skilled at either (or is willing to put more time into it) will be more successful.
