This sound comes from EverQuest, the influential MMORPG released in 1999. The level up ding became memorable for players because leveling in EverQuest often took real time and effort, so the audio cue carried a strong sense of payoff. Over the years, the clip spread beyond the game into gaming forums, videos, and nostalgic MMO edits as a shorthand for progress. It still gets used because even people who never played EverQuest can immediately understand it as a classic achievement sound.