Some simple risk of ruin math introduced here.

Assumptions:
- The whales have enough capital to try and break the bank without going broke.
- JD is considered "ruined" when the bankroll drops from 30,000 BTC to 5,000 BTC.  Considering the panic already seen among investors, this is a very conservative estimate.

With a 1% max bet the risk of ruin is surprisingly high:  18.2%

With a 0.5% max bet it drops drastically to: 3.3%

With a 0.25% max bet it is miniscule: 0.11%

Also, Kelly criterion does apply for the best long-term ROI, but with kelly betting you can never go broke.  Just eventually the max bet would get into the satoshis and nobody would play.