Eh, I think people list all kinds of reasons for why they want in. He did indicate he was prior service and wanted to finish a goal of his (i.e., becoming an officer). I'd expect plenty of people want to join the military for reasons rooted in self-interest. When people ask me why I submitted, I generally tell them it's because I'm super bored of the corporate environment and want to do something more meaningful, hands-on and exciting. I've got plenty of additional reasons and sub-reasons, but I don't generally stray toward the typical rhetoric (e.g., serve my country, be a naval officer, etc.) when offering up explanations
And hey, I'm sure joining the military later in life is all the more reason to be concerned about the specifics of the career benefits. But I, like Jon Snow, know nothing.