Why do we earn points here? I can't understand the goal :)

Hey Anna, as of now there's no particular goal of earning points. Rather it's an indicator of your active-ness on PH. You can earn points by actively contributing across Product Hunt. Contributing includes: posting products, creating discussions, and engaging in conversations. You'll gain points when other community members upvote, cheer, or in any way appreciate your contribution.

I think it's just for the sense of achievement.

It's part of social credit system. Scores are an objective way to tell who the most active members of the community are. Without them, it can be hard to tell. Not so different from any other metric we track as humans 😃

I think its to boost authority on the platform - you see someone with a long streak - lots of points - tons of followers etc. You presume they are someone of note on PH. It MAY also give more weight to their interaction with launches / upvotes etc.