A lot of people would like to retire early whatever their job. It's increasingly hard to plan to do that these days, any more than you can plan to become independently wealthy.
You cannot plan to become wealthy, but you can attempt it. If you don't try it you've already lost, else you do have a chance.
The point of my original post is: 2016 is a really good time to be a developer, but still, if you don't do something extra you may have it really tough by age 40 (don't blame the "ageists"!).
You can be up to a number of things:
- launch your own startup
- become a freelancer, hack your way into great rates