Just wanted to offer a different perspective. Some people come here to play games, not to socialize. Some of them may be on the spectrum. These people see saying hi or gg as an unnecessary ritual that adds nothing to the experience for anyone. I'm sure you do not feel this way, but some people do. It may be difficult for them to see this through your eyes.
I also think that this is not about the right and wrong. It's just that people are different, so it's not necessarily that there is a single "right" behaviour here. It is difficult not to feel a bit disappointed, if you are up for chat, but no one wants chatting, but if that's what people want (or rather do not want) to do, it's up to them. If they are silent it does not mean they are unfriendly. It's just they have different priorities on bga and enjoy different aspect of it.
You might find it more gratifying finding yourself a nice board game related discord server where you can chat away, or finding a group of like-minded people here, on the forums (although admittedly, this forum itself is not very active) and adding them to your friend list to play and chat with them. Bringing a few real-life friends here to play with is also an option.
I did have to leave a real-life gaming group once on the account that people gravitated more to socializing than to playing games, so I'm talking from experience, but I was able to find one where we can just focus on playing and enjoying the actual games - so just find your niche!
And of course, I agree with Jest Phulin - keep saying Hi, and engage with people who chose to participate!