Yeah, that argument can be made, I see what you mean. Kind of like the traveling just to post a bunch of flashy pictures on Instagram thing. Even when that is the case, I think a lot of those people who do outdoorsy stuff partially for the pictures, geek stuff, etc. do receive some pleasure from the hobby or activity itself and so it's not all just for "approval-seeking" or showing off on social media.
On the other hand, can't materialism and approval-seeking be positive in some aspects? For example, materialism and keeping up with the Joneses' incentivizes people to continue working harder and getting better jobs, thus helping them stay the course to prosperity and keeping high-paying jobs, or motivating them to get better jobs.
I know the same argument can be made that materialism causes people to be over-spenders and end up in a whirlwind of debt, but for myself, I think I might have had more goals and been more motivated when I cared about those things.