Why does achieving some success in research not feel satisfying? Are our academia research minds just so trained to constantly climb our mental mountains that when achieving some success, one feels, "that was it?", even when the past leading up to the success was absolutely brutal in terms of work load and stress and creative thinking, so that one would think the feeling would be more joyous.

Does it always just kind of feel that way?  Does the rewarding feeling dissipate very quickly?
The reward is pretty temporary.

There are definitely dramatic high points in academics- publishing a paper, making tenure, graduating a student, etc. Those are cool, but those are relatively rare occurrences. You can't judge the experience of climbing a mountain just based on how it felt when you got to the top. If you hate the entire experience of climbing up and down then you're spending 99% of your time hating the experience and only enjoying the dramatic moment.

Academics as a profession has no ending point, there's simply a process of continual improvement. No one is ever going to publish the last paper that explains everything and your teaching material is never going to get to a place where it's finally perfect. You're never going to get to the top of academics and declare that you're finished, so the day to day work you do is what you need to enjoy in order to feel fulfilled. This is true in most careers.

You need to define success clearly for yourself. What does it mean for you to be successful? Is it publishing so many papers in a year? Is it solving some problem close to your heart? Is it getting tenure? Is it becoming an editor of a journal in your field? Is it making a lot of money? Is it having time with your family? 

Success is something that feels good when you're doing it. Everyone has hiccups, doldrums, or other low points in their career. That's normal, and not every day will be a good day (or year, or project, or paper, etc.). But, your routine work should be something you feel is enjoyable and fulfilling. If not, you're going to burn out sooner or later. This is true for any career, not just academics.