Why is there a need for an afterlife (or heaven) at all?

Hello Rabbi,
I often hear rabbis talk about the importance of investing in this world in order to buy the next world, emphasizing that this world is nothing more than a “corridor before the parlor.” But the more I try to delve into it, the more I fail to fully understand the magnitude of the matter, and in particular – why it is supposed to attract me or speak to me.
After all, there are quite a few people who live good and fulfilling lives in this world. Even when there is difficulty, they know how to see it as part of the process – like a challenge in physical training or learning. Not only do they not suffer from it, but they even love the difficulty, understanding that it leads to a good result and a deep sense of satisfaction.
There are also people who find meaning in the process itself – they live life as it is, enjoying the moments, the path and personal progress, without looking for something infinite beyond. They do not aspire to the afterlife – not out of disdain, but because they do not understand what it really is, and they have no need for something they have never experienced.
And this is a truly fundamental question for me: How can I desire something that I have no access to?
I have often heard quotes from the Sages that say that one moment in the next world is worth all the pleasures of this world, but the truth is that this statement feels distant to me. It doesn't touch me emotionally, doesn't fill me with aspiration. It sounds too abstract, almost theoretical.
I have also heard lectures from very wealthy people who say out loud that there is really no significant difference between someone who earns a million dollars a year and someone who earns a billion. The lifestyle hardly changes, and the daily pleasures remain the same. They continue to chase money only out of an inner need for competition, not out of a real lack. I feel like it could be similar in the afterlife: it may be full of pleasure, but if I don't feel the lack, I'm not sure I really crave it.
True, I have heard the claim that in the next world man becomes a wider "vessel" that can contain a completely different kind of pleasure, a supreme spiritual pleasure. But here too the question returns: If now I do not feel that I lack anything, and if I am happy with my existence as it is – what should motivate me to change my life just for a future pleasure that I do not know, do not feel, and am not even sure that I desire?
I ask all this out of a genuine desire to understand, and not out of an argument. I would be very happy for an answer that could shed more light on this point for me, perhaps from the sources or from life experience.
Thank you and have a good day.