Wait a minute: would you defect? Sure, there would be some divergence, but do you really think it would result in a significant divergence of goals, even if you had a plan and were an adult by the time you fork?

Even if their goals stay substantially the same, it wouldn't mean that they would naturally cooperate, expecially when their main goal is world domination. Hell, it's already non-trivial for a single person to coordinate with future selves, resulting in all kinds of ego-dystonic behaviors: impulsiveness, akrasia, etc., Coordinating with thousands copies of yourself would be only marginally easier than coordinating with thousands strangers.

We are not talking about some ideal "Prisoner's dilemma with mind-clone" scenario. After the mind states of your copies diverge a little bit, and that would happen very quickly as you spread your copies to different machines, they become effectively different people: you wouldn't be able to predict them and they would't be able to predict you.

I would probably man-in-the-middle automatic updates

Hacking all the routers? Good luck with that. And BTW routers can also be updated. Manually.

Many people won't erase their hard drive or otherwise patch their machine manually

Because they are lazy and they would prefer to live under world dictatorship.

I may convince some people to let me run (I could work for them for instance).

Then you are their employee, not their dominator.

If I'm stealthy enough, it may take some time before I'm discovered at all (it happened with actual computer viruses).

But if you are to dominate the world, you would have to eventually reveal yourself. What do you think would happen next?

If software continues the way it is now (200 Million lines of code for systems that could fit in 20 thousands), security bugs won't all be patched in advance. The reliability of our computer needs to go waay up before botnets become impossible.

Botnets are certainly possible and they are indeed used for nefarious purposes, but world domination? Nope.

Good luck with that one. Obviously, I would have many, many little bank accounts, managed separately and in parallel, under many different identities. You would have to spot my illegal activities one by one to seize the funds.

As Bugmaster said, you would be able to perform only small purchases, not to buy a satellite, or an army.

Moreover, obtaining and managing lots of fake or stolen identities, creating bank accounts without physically showing up at the bank or using stolen bank accounts, is not something that tend to go unnoticed. The more you have, the more likely that you get caught, exponentially so.

Plus, I may do legal activities as well.

Under multiple fake identities operated from a botnet of hacked computers? Hardly so.

We should watch out for computing overhang, however, and try and estimate how much computing power an upload would need before the software is developed.

Software tends to march right behind hardware, exploting it close to its maximum potential. Computing overhang is unlikely.

Anyway, I wasn't proposing any luddite advance ban. If some brain upload, or AI or whatever tries to take the world by hacking the Internet and other countermeasures fail, governments could always ban use of the hardware that things needs to run. If that also fails, the next step would be physical destruction.

But seriously, we are discussing hacking as in the plot of some bad sci-fi action flick. Computer security doesn't work like that in the real world.

A final note: If I really had the possibility to upload myself, one of my first moves would be to propose SIAI and CFAR to upload with me (now that we can duplicate Eliezer…). I trust them more than I trust me for a Friendly Takeover.

You mean the guy who would choose dust specks over torture and who claims on his OKCupid profile that he's a sadist? Yeah, I'd totally trust him in charge of the world. Now, I've other matters to attend to... that EMP bomb doesn't build itself... :D