In cryptocurrency trading everyone tries to trade in some of his favorites by applying some strategy. Any technique can be applied in this case. But it will depend on who trades. The strategy your friend has applied is certainly good. I wouldn't think of that as a negative because emotions are useless in the trading world. Whether you consider him a selfish or something, I think he made a good decision. If a trader can patiently wait for the bullish and bearish periods of the market, the chances of making profits are high. But not everyone can wait that long. Your friend does that. I will definitely support his strategy.
Everyone may have a different strategy in trading. I don't think it is because people choose their favorite strategy, people choose the most effective strategy to use in the current market condition. Sure, we also need to have sufficient knowledge, so we can use a certain strategy in a proper way. Even if everyone can have a different level of understanding, but I think it still can work well as long as we have sufficient knowledge/skills.
Anyway, if we want to wait for a long time, we are better choosing investment. In trading, we have a goal for a short term, it can be daily or weekly. If we target to get high profits in few months or few years, it is categorized as investment.