Can a HFT-knowledgeable commenter chime in on the viability of the Sharpe ratio here?

From a physics perspective, it appears that the Sharpe ratio of 4.1 is roughly equivalent to a 4.1-sigma claim that their algorithm is better than random trading. I can't check easily, but I'd guess that the movement of Bitcoin prices isn't normally-distributed (looking at the paper's time series suggests that there's more low-frequency power there). If so, I'd guess that a more robust measure of the claim's significance would show it to be less significant.

Put differently, I'd guess more than 1 in 15,000 random sets of 2872 trades (their number of trades) would yield comparable profit. Furthermore, a simple buy-and-hold would've yielded a 20+% return over the same period.