In the midst of a market as volatile as the crypto market, I think one way a trader can measure success or ensure he's being successful in his trades is by via a trader's ability to stay calm and maintain absolute calmness and control emotionally during a fluctuating market, because this is often the period when traders end up making impulsive decisions, as a result of emotional instability caused by fluctuations in the market. If a trader can manage to maintain emotional balance during such market conditions, he'll have the opportunity to make better decisions that'll make him stay in profit or mitigate the losses. And by that, he'll gradually learn from the market condition and also look for alternative ways to be able to adapt to different market conditions, both the favourable and the unfavourable conditions.
Because I'm strongly of the opinion that being successful in crypto trading isn't just about making profits but also about avoiding losses as much as you can, so even in times that you don't make profit but is able to avoid losses, that could also be considered to be a huge success.