Why the recovery hurdle grows
After losing a fraction d of starting capital, remaining capital is 1 minus d. To return to one, the required gain is d divided by one minus d. A 50% loss leaves half the original base and therefore requires a 100% recovery gain.
What this does not predict
The calculator is arithmetic, not a forecast of time to recovery or the probability of a profitable strategy. At a 100% loss, no finite percentage gain on the remaining zero balance restores the account.