That is not too far from believing in the afterlife, if you come to think of it.
It’s extremely far. One has a chain of reasoning and supporting data. The other does not.
They’re both assumptions, since everything about the future is an assumption. But some assumptions are “better” than others, for lack of a better word.
On the other hand, believing that your actions have consequences, and that you will pay for your mistakes, is a very good assumption. But in the sense that you mention, it's "unsupported". This lack of evidence may lead me to conclude that societies are hung by a thread, and that collapse is imminent. It could be, but societal collapse simply hasn't happen after an unexpected, global, unprecedented turmoil.
Why some assumptions are "better" than others? THAT is a very good question. My take is that there aren't a priori: some societies believe some assumptions, and survive, and others don't. In a sense, to me, assumptions are only good in retrospect, and it's an idea that "feels" correct rather than something I can "prove".
Touching something too hot transfers excessive energy to your skin and registers as pain.
Walking without looking at where you’re going can cause you to not notice uneven surface and affect your balance causing you to fall.
Attending a higher education facility and obtaining credentialing and skills in a field with high demand in order to be able to trade it for money so that you can then use that money to pay for shelter and food and medicine.
The above are all assumptions until they actually occur, but they are different than assuming an afterlife simply because you feel like it (for example, it satisfies one’s ego to assume a piece of them is immortal. Not that there’s anything wrong with that, do whatever makes you feel good).
Ironically, basically all physicists of the last ~100 years went through university in order to study physics. What do you think was their "rationalization"?
I suspect most people who believe in an afterlife have a chain of reasoning and supporting data to back up their belief, too. Personally, I don’t believe that reasoning is sound or the supporting data is high-quality or convincing but I also don’t think the distinction you’ve drawn is really all that meaningful.