I wonder, what are the plans of those people on SO (later on Meta), who have reputation way over 10k? Apart from being elected to a diamond moderator, what do you want do with your enormous amount of reputation?
No, no, forget that joke pal!
At one point I was really interested in whether or not I could get on the front page of users. A sort of interesting challenge. Now I know that there's little likelihood of me ever moving up the rankings beyond my current level. As far as reputation goes, I'm basically doing well to keep my current position.
For me the main, continuing motiviation is a desire to help and to learn. I actually find that I learn more by helping. That's what keeps me coming back.
Reputation doesn't matter. If you're on SO to get reputation then you don't belong on SO.
Seriously, being 10k shouldn't change anything other than perhaps enabling you to help new users and clean up messes better with the moderator tools. We're here to help people and to learn. Gaining reputation is a side-effect of this and should not be seen as an end to itself.
I was about to say that I don't have any plans.
But then I realized that would be a lie. I'd like to have a gold badge. I'm a bit envious of people who have gold badges. They have three colored dots after their reputation number, and I only have two!
I want some tag-expert badges. Apparently, I'm too much of a generalist, and despite my efforts, Generalist remains unimplemented. :(
Also, page 1 would be nice.
Edit: Got my php badge. So now I am officially an expert in what I consider to be the second worst language in broad use. Yay.
My goal is to stay highly ranked in my favorite tags.
The best way to learn is by trying to articulate your thoughts to someone else, particularly without verbal communication. As a result I think my ongoing participation is making me better, well less worserer, at understanding and interpreting requirements and communicating complex technical issues. This can only be a good thing.
I also find questions just outside my comfort zone interesting and challenging, and I've ended up writing (and using) a few little widgets that wouldn't have occurred to me without trying to answer someone's question.
Once I reached 10K I set myself a few arbitrary targets and ongoing benchmarks. Some are readily achievable, some longer term goals. They either give me something to aim for in terms of rankings, or learning new things, or helping out with unpopular questions
I've been writing GreaseMonkey scripts to help learn JQuery and help me track those goals. To reinforce my first point, writing this list down has made me think about my goals more precisely and I've come up with a few more ideas for GM scripts.
After you hit 10k, the only thing left fighting for is your place in the list (if that matters). I was on a big "get to the next page" kick for a while after I hit 10k, but now that I have Meta and SuperUser to play around in, I am not too concerned about my score on StackOverflow anymore.
I want to get onto the first page. That is all.
I just want to be on the first page of some tag ... Which gives me an idea ... I'm going to start my own tag ... muahahah.
When you get that much reputation, it matters very little if actions have negative rep consequences. Downvote all day, who cares.
Personally I thought it would be great if you could elect to display your own rep at a limit you choose. You'd actually keep a real, higher, and growing rep, but could decide say that you wanted it displayed as 68k.
Otherwise it's as useful as the mileage I have with 5 different airlines. Its just there to expire. Though I really appreciated the once Swiss Air lowest tier "gift" of a Sacher Torte Air freighted to you direct from Café Sacher in Vienna's Hotel Sacher.
If I had plenty of rep, I would use it more for bounties on my questions - usually, I ask harder/newer things than the average. My only target was to reach 2k to be able to fix formatting.
My take on Meta? No need for 2k here, so I just try to ask questions about the sites, provide feature requests, and perhaps encourage people with bounties to improve things around.
It seems to me that once you are fully trusted by the system (as in the stackoverflow stack) all your reputation means is that it is a sign that you are considered to be a respected member by other members of the site(s). However, it seems to me that the silver and goal tag badges such as C# or Java are going to be more relevant to most users as they will be a sign that a user is considered to be a respected authority on a subject.
I'm hoping to cash it in for options in StackOverflow LLC ... is that on the table at all? :)
I think that anyone behaves differently once they've joined the 10K club:
By the time you reach 10K you're probably already hooked... you already developed a good learning ability, quick thinking and the passion to help other people.
So I guess that if you crawled so deep into the rabbit hole - by this time (10K) there's no way back...
After reading @Welbot's answer and the very interesting conversation in the comments as well, I think there's a very important point that many of us are missing:
Today there are more and more high-tech companies and recruiters that check your SO profile!
By helping other people you're actually not only learning & developing your abilities, but also helping yourself by making a good "first impression" - even before you got an interview!