You are so right. I think we all fall victim of such thinking of attainment at one point or the other as described in this post, but I believe we snap out of such thinking pattern differently and faster than each other. See! It is almost natural for someone to have the feeling of arrival when they have achieved a particular feet, this comes as a result of the goal for that phase. But maybe as part of what should be done to help in such situations as this is:

Creating a bigger goal out of the smaller one we are trying to achieve for that phase of life, that way, we will know we are just getting started even after attaining the small version.

Many of us here thought that leaving school with a good grade was all that matter. Fast forward to having those grades, we all started looking for jobs and most times we find the jobs thy don't even require the paper we carry about, calling certificates. I believe strongly that blowing out our goals in a bigger spectrum helps to limit the feeling of achievement when we achieve just little. Thanks for sharing this @gbenga