New Kid On The Block Who Doesn't Know The Rules

I moved to this new city two months ago. My job's cool, but the community feels like a mystery to me. Everyone seems to know each other and have their own little cliques. I started working out at the local gym thinking it might help me meet people, but here's where things get weird. First off, there's this guy named Mark who always greets everyone with a big smile. But he doesn't say hi to me, ever. At first, I thought maybe we hadn't been introduced yet. But after talking to other gym-goers, I found out that it seems normal for him to ignore new people until they've 'earned' his respect. So, I decided to just be friendly and try to earn this unspoken badge of honor by working hard and being polite. Maybe he'll eventually come around? But then there's also Sarah who's been super nice from day one but told me that Mark is the gym king and doesn't appreciate people coming in unless they're already established. Now, I'm trying to figure out how much of this is just a strange culture thing or if I've really done something wrong. Should I be more aggressive at the gym like everyone else? Or should I stick to my polite self and hope for the best? Am I being too sensitive about Mark's behavior, or does he deserve to hear from me that his approach isn't welcoming for new members? What would you do in this situation?