One cannot help but wonder if negotiations is the only skill that is needed to get ahead in life. The examples of people who accumulated a great deal solely relying on that trait are countless, including the ones who, with their lack of understanding the basics, did things that had negative consequences even decades after. Negotiation is arguably the most important of all under the “people skills” umbrella.
Clearly, the higher you score on agreeableness, the less you get your way, which means you probably are not very good at negotiations. But even though not everybody possesses that trait, one has to at least learn how it works so as not to get screwed over. And to the degree that it can be improved, it should be done, with all seriousness.