I have gotten some nice knowledge concerning bitcoin investment in this thread and am still learning in the process 700 pages of bitcoin knowledge and still counting all thanks to JJG and other reputable fellow in this thread.
If you are a HODLer keep buying and hodling bitcoin if you are still procastinating on when to buy you can buy today if you have your discretionary income already starting buying and HODL you can begin with little amount and gradually increase according to the level of your discretionary using the DCA strategy.
Just buy bitcoin and HODL in summary.
Having what it takes to buy and hold is a different thing from not having what it takes to invest in Bitcoin, there are individual who has the money and all takes to invest in Bitcoin but they keep on procrastinating and these category of people I see them as unserious people because anyone who has all these... And is still procrastinating even if the person eventually start, they can not maintain their investment or hold for long because their knowledge or understand about Bitcoin is so myopic. In Bitcoin investment though having a discretionary income is good but
it is not compulsory that you must have a discretionary income before you can be able to invest, you can actually start and make sure to set everything in order so that you don't get choked up and the truth is you can not have everything ready before investing but along the line things well fall into their right places and you can even increase your initial amount.
I totally disagree with you on this, your investment in bitcoin should be coming from your discretionary income so that you won't need to dip hands into your bitcoin investment and also to be able to hold for 4 to 10yrs or longer as per your investment time line. So it will be wrong to invest an amount that will make you not be able to cover up your expenses.