Deathloop Lore

In death loop many of the eternalists talk about looping, talk about seeing you the next loop, are very risky with their lives, like they've been stuck in the loop for a while and are aware of it.

Except for all the eternalists, save 1, they have no memory of looping. The day is their first day, so why would they be so confident that the loop is working. If I was put into a looping time project I wouldn't believe it was working until I had some groundhog experiences going on.

Is there a good in universe reason for the eternalists to act so confident?

-- I just finished death loop, my patient gamer moment