There are plenty of situations where people do things for benefits that they personally won't see. Like people who decide to avoid messing up the environment even though the consequences might not happen in their lifetime or to themselves specifically. Or scientists who work to add knowledge that might only be properly appreciated or used by future generations. "A society grows great when old men plant trees whose shade they know they shall never sit in". The setup would just be the dynamic of society recreated in miniature with a society of yourselves.
If you psyche yourself into the right mood, knowing that the only remaining thing of consequence to do with your time is your task might be exciting. I imagine there's some inkling of truth in https://www.smbc-comics.com/comic/dream. You could also make it so all of your upload-selves have their mental states modified to be more focused.
If such a technology existed, it would definitely require intense mental training and preparation before it could be used. One would have to become the most detached buddhist in order to be the sort of person who, when cloned, did not flip their shit over discovering that the rest of their short time alive will only to further the master branch of their own life.
It would change everything about your personality, even as the original and surviving copy.
I really think that if you truly believed your identity is defined only by things you share in common with the original, then you as the upload would have no fear of deletion.
Most people define identity in part by continuity of experience, which is something that wouldn't be in common with the original, but I think this is just superstition. It's easy to imagine setups that preserve continuity that come out with identical results to setups that fail to preserve continuity (https://news.ycombinator.com/item?id=26234052), which makes me suspicious of it being valuable. I think continuity of experience is only an instrumental value crafted by evolution to help us stay alive in a world that didn't have copying. I think if humans evolved in a world where we could make disposable copies of ourselves, we wouldn't instinctively value continuity of experience -- we would instead instinctively value preserving the original and ensuring a line of succession for a copy to take the place of the original if something happened to the original -- and that would make us more effective in our pursuits in a world with copying.
Now if I was the upload, and I learned that my original had died (or significantly drifted in values away from myself) and none of my other copies were in position to take over the place in the world of my original, then I would worry about my mortality.
If you psyche yourself into the right mood, knowing that the only remaining thing of consequence to do with your time is your task might be exciting. I imagine there's some inkling of truth in https://www.smbc-comics.com/comic/dream. You could also make it so all of your upload-selves have their mental states modified to be more focused.