Hold on for dear life is a strategy of someone who is overly concerned about their bitcoin investment, and it is not the meaning of HODL.  That description was made up by mainstream trying to portray bitcoin in a negative way.

There are ways to invest into bitcoin aggressively but not so aggressively that you are emotional about it.  Also if you spend a bit of time learning about bitcoin while you are investing into it, you may well start to appreciate that even if it is not guaranteed to go up, at least it is not guaranteed to go down in purchasing power, which is the case with the dollar (and all other fiat currencies).  Many folks investing into bitcoin and holding it come to realize that it is a good hedge against dollar debasement, and surely if you continue to buy bitcoin and hold it long enough then there are decently good odds that BTC price curve trajectory is  going  to continue to be up and  to the right, which largely means that your options go up, especially if you can get through a cycle or two...and yeah, there are no guarantees, so each person has to figure out a position size that is comfortable to his financial and/or psychological circumstances, which should  not be zero. 

Even though around 99% of the world's population do not have any bitcoin, it would be better for them to get some exposure to bitcoin rather than staying on zero or even being underexposed  to bitcoin.  In recent times, I have frequently been suggesting a 5%  to 25% starting  exposure to  bitcoin, yet individuals are responsible for their own choices regarding their exposure level and if they want to be on the lighter end of  the range or the heavier end of  the range, which their chosen level of exposure to BTC also might also relate back to their finances too rather than merely their beliefs about bitcoin.