It doesn’t. Concurrent literally means how many people are playing at the same time, in that specific moment. That’s it.
Example:
If in a day 1,000 people are playing at 2pm US time, and another 1,000 are playing at 2pm Japan time, the concurrent number for that 24 hour is still 1,000, not 2,000. Those are two separate peaks, not a combined total.
On launch day, everyone that's hyped tend to login around the same window regardless of timezone, so the concurrency naturally shoots way highe
You can have a game with millions of owners, thousands of daily players, but only a small concurrent number depending on time zones, habits, and peak hours.
Just… please. Learn what “concurrent” means before turning every Steam chart into doom posting.