If the price of SOL keeps rising, this creates risk for Will. For example, if the price of SOL continues it's uptrend and goes to $175, the party who bought Wills short calls would be able to execute the option and purchase 1 SOL worth $175 each, for $150 each. In this scenario Will's loss is: $25 (underlying price - strike price) - $5 (the premium which is still kept by Will and helps offset some loss) = $20 loss per option.