the decline in unit net value is not the loss of principal.

if the net value after falling is lower than the net value of the fund when you bought it, you will lose the principal if you redeem it at this time. But if you don't redeem it after the decline, and the fund finally rises back, you won't lose the principal if you redeem it at that time.

the unit net value of the fund falls and then rises again. In terms of unit net value and total principal value, when it rises back to the value before the fall, the total principal is equal. However, if the fund falls by half, it will take 1% to return to its original value. For example, a drop from 2 to 1 is 5%, but from 1 to 2, it takes 1% to get back to the original cost. Simply put, the bigger the drop, the more difficult it is to get back to the original cost.