Maybe most of those proposing investment of what one can lose are suggesting that the price of Bitcoin will get to zero someday or that Bitcoin might be banned globally thereby making it worthless. These are baseless conjectures in my opinion.
Don't get it wrong JJG has already explained why that phrase in bold means below
the idea about investment amount is to invest no more than you can afford to lose.. which largely just means make sure that you have your expenses covered, and that even if the investment dropped a lot you would not panic because you have already considered the possibility that it might drop...
but since we are considering longer term considerations in this thread, many of us already seemed to planned to not sell in the short-term - even though it is difficult to talk for everyone
I agree with you, my focus is on the right time to buy, not on the right time to sell right now. Just like the topic of this discussion, "Buy the DIP, and HODL!" that is what I want to do, and I regularly check this place to see the strategies people here are using to get more bitcoins, so I can learn, I do not want to learn about selling.
Using the DCA method to accumulate bitcoin has a high advantage to increase your bitcoin portfolio fast as a newbie that just started her bitcoin journey compare to the other two strategy which is lump sum and buying at the dip. This is because it gives you the opportunity to buy bitcoin regular at different prices and as long as you are on a long term investment, it will also lower the risk attached to bitcoin investment. Just set an amount that will you will use to buy weekly, monthly or quarterly that will not affect your monthly expenses. Also set aside emergency funds and reserve funds so that you won't be tempted to sell your bitcoin when you face some financial challenges, as those funds will take take of whatever arises. If you have extra cash, you can save them for buying at the dip. You should start your bitcoin investment now and don't wait for the dip because nobody knows what will be the next movement of bitcoin price. The earlier you invest the best for you.