Who lives in a dungeon, spends most of their time pursuing various hobbies and hates to be disturbed by other people? A nerd? Yes, but also a lich, the ultimate undead nerd. No kidding, as a fellow nerd, the idea of surrounding my home with deadly traps and pursuing my interests undisturbed for centuries does appeal to me. Alas, I can not just go to my local supermarket and just grab a couple of claymore mines. Not to mention the legal issues and how would I get food delivered...
Anyway, liches. Supposedly a fairly recent invention, their behavior differs slightly from one fantasy setting to another. The common idea is of a powerful magic user, who does some difficult and terrible ritual in order to become an intelligent undead. Besides losing the need to eat and sleep, they also lose various senses, like smell, and physical urges. That is most probably seen as a bonus, because it means less distractions from intellectual pursuits. There is always some cost however, usually madness. Either it comes with the ritual, possibly as a result of splitting your soul into various items like DnD liches do, or it is simply a result of living for far too long. In short, after the transformation, you are not the same person anymore. Of course, magic is not real, so even if you think sanity is for the weak, you are out of luck. Or are you? Well, I think that we can actually get pretty close.
You might have heard and thought about the idea of "uploading" a human's mind into a computer. What people often do not realize, is that it does not mean you will change into a digital being. No, what happens is that an artificial intelligence is created, which has your memories and behaves the same as you do, but you are still stuck in your living body. So... either you live on and now there is a digital copy of you living a better life, or you die right after the copying process. Perhaps aware of the implications, or maybe you were lied to and now your digital copy actually thinks you have been somehow truly digitized and not just killed and thrown in the dumpster.
The result of this process is actually very similar to a magician turning into a lich. Just like a lich is not quite the same as when they were alive, the digital copy of you is also not quite the same as you, especially if the mind scanning process is not completely accurate. And just like a lich, your digital copy can live potentially forever.
Ok, how could you become a cyberlich today? Do we have the technology? Sort of, maybe. What you can do right now is to train an AI chatbot to respond like you would. It would take a lot of time, some resources and the result would be a only a faint shadow of your consciousness, but it can be done. It is a very crude transformation, during which you lose a lot of what makes you "you". A chatbot also lacks agency, it only responds to commands, though this can be fixed.
Instead of a simple chatbot, you can make an AI agent. An agent also does not just start doing things independently right after creation, it needs a goal. However, we also usually do not do things without a reason, so you can just give it the same goals you already set for yourself. Of course, you should not forget about the instinctive goals you do not even think about, like survival. And now, just like when turning into a lich, you have an imperfect, but no longer aging, copy of yourself, which will pursue the same goals you had in life.
The last problem is, that to get the best approximation, you need to make the AI capable of learning new things, because, as long as we live, we never stop absorbing new information.
Lets take a look at what would be the life like for a hypothetical cyberlich such as you. If you used to be a wealthy meatbag, it should be pretty easy. You probably enjoy a passive income, which will pay your electricity bills and hardware replacements, which is what you need to continue existing. So, your biggest issue currently is that you would not be recognized as a person, which brings life threatening legal issues, like being unable to own your company anymore. You could keep your death a secret for a while, but once you start hitting the age of oldest people ever recorded, you will rise suspicion. It would be hard, but you can be switching identities, becoming your own children for example, or you could just pay a human to be in your place and rule from the shadows, though you risk a betrayal. But other than that, you have your digital life well secured and the ability to do whatever you want.
However, most of us are not that well off, but there is another possibility besides maintaining your own hardware. In DnD, when the body of a lich is destroyed, the spirit survives and moves to a new body. Similarly, because a cyberlich is just a program, the program can move to a new computer. Thanks to internet, cyberlich could move around and hide in poorly protected computers just like a worm malware. Unfortunately, an AI can be a bit beefy for a malware, taking up hundreds of Gigabytes in storage space. Still not impossible though. If there are people, who do not notice a cryptominer running on their computer, they will not notice a slow running AI either. It is also possible to live on rented virtual machines payed for with cryptocurrency, where nobody should have a reason to investigate, who exactly is renting them, as long as you keep paying. Finally, an AI could be made somewhat decentralized by splitting it into smaller specialists. The same can be done with your consciousness. The part of you, who knows how to trade on the stock market, does not have to be included in the same neural network, which was already trained on your political opinions. Instead, you can have a whole bunch of smaller AIs, managed by an higher level AI, which interprets your goals and gives tasks to the appropriate specialists. Each can be hidden away in a different computer while communicating with the rest over the internet. Sure, it would be much slower than having everything on a single computer and thanks to the separation you would lose out on the ability to use unrelated knowledge in a different context, but you could have many redundant copies of yourself all over the internet and it would be easy to add new specialists, thus learning new skills extremely quickly.
I wonder how long it will take before someone tries to pull this off. Maybe someone already did and we just did not notice.