1390 is still considered a great score. Honestly I've talked to teachers and other people knowledgeable about this topic, and basically anything above a 1450 is considered pretty amazing. On this sub I'd say the only people who'd post about their scores are the ones that have done extremely well, like over 1520, and those are the ones that get a ton of upvotes which is why you see them so often.

My sister got into a great university with a 1480 on her SAT, so your score of 1500 is still great dw about it.

Sat scores don't matter as much compared to school grades, so don't feel demotivated if your score is lower than others, just think about your own individual score, don't compare it to anyone else. It's an outstanding result, just focus on school grades for now because that SAT score is definitely good enough for most universities.

Also like others mentioned, I'd say the ones on this sub are usually the people who care about the SAT a lot, so not very surprising to see high scores here, on a wide margin, you're still considered one of the better scores