You can care about things, but it seems preferable to care about that which you can change

That’s a reductionist and wrong reading of the argument I made.

You said "can’t change". I observed that deciding you can't change something is self-fulfilling. Your argument from that point still relied on the assumption that you can't change it.

Before you decide not to care about something, you are supposed to make a deep assessment to see whether you can change it. It is only after you’ve determined that the thing can’t be changed that you can choose not to care about it.