Sure, that's a good plan for people who want to play in the safe zone. However, most investors are in the crypto market to get rich quickly. 20% might seem good for people who are doing this on the side, but others' plan is, the greater the risk, the better the reward. And cryptocurrencies don't just reach 95%+ profits, in the long run, 1,000%, 5,000% or even 10,000% are not strange to the crypto scene.
It is not a bad decisions to rely on the middle or on our comfort zone the thing is we really need to be comfortable on our trading and investment because if we stress ourselves and think about the possible risk and change we could have all we would do is to panic and to make a bad decision in the end.
If we will all become greedy then there is nothing it can do with the bitcoin life that is why we need to be the shoulder and helping hands of each other, we need all to share ideas for all of us to become successful here, if we will not help each other I don't think cryptocurrency will exist forever.