It cannot be denied that buying and holding bitcoins is the safest way to invest in bitcoins, but for those with the ability and skills to trade, trading to increase the amount of bitcoins is not so bad. Just because we can't win at trading doesn't mean everyone is like us. I have a friend who makes a living as a day trader and so far he's been fine. It can be said that everyone has different skills, so we should know who we are and what our strengths are so that we can make appropriate choices that bring the best benefits to us. Don't imitate others just because they are successful that way, each person has a different path to success.
I don't think they were trying to conclusively decide for everyone, they where probably mapping out dangers from their own perspective on the dangers, stress and anxiety to be faced while doing more of trading than holding. What now causes majority people to trade is due to greed and lack of patience to hold for long time, they quickly want to earn profits not even test running if they are capable of doing it and we can see some of them at the very end left with nothing to talk about.
I don't think it is correct that majority of those involved in Bitcoin traders because if you smell the air, you will realise the number of people actively trading Bitcoin have diminished so much following the transition of many traders to short term holders, who I think are in the majority now.
Most people hold just within Bitcoin market cycle of 4 years, buying during the bear season and selling during the bull market like some are already doing now. Some of the whales go about Bitcoin investment this way as well.
Following the realisation that long term holding is actually the best, many people are gradually tilting towards that direction just like it happened between trading and short term holding.