"Ultimate" success for a dev?

I don't know what that would be, so I'll be answering that around my experience.

Start really poor, so when you start making good money, you value and appreciate it.
Work for a company (Startup/MNC doesn't matter), and build your network with people/clients.
Work really hard in the beginning era and fail as much as possible.
Quit said company and build your own client-base, cutting the middle men out of the equation.
Work on your terms after that, remotely obviously.
Years down the line, come up with your own idea and start a company which makes enough money to retire with ease, not worrying about saving up for retirement.