Having a stable source of income is not the only thing that will make an invest hold for long term there are others things that is attached to been able to hold for a long term which are, good management skill, patient, determination and some others. Now if an investor has a stable source of income and doesn't have a good management skill, that Investor will squander his money and even the discretionary will not be kept because the ability to keep his or her discretionary, emergency funds etc will not be there that is he or she won't consider them and again even if and investor has a good management skill and he or she is not patient the investment will still crash because he will be tempted to sell off.
agree with you here, however a successful investor is one who manages to combine all aspects in his investment,
- has a stable income
- is able to manage money well
- is patient and has full confidence in what he is investing in
- has principles
we all know that the price of bitcoin today is $87,500 imagine if you buy bitcoin at a price of $100k if you don't have patience and determination then your principles will collapse, besides if you use emergency money or the only money you have then you will definitely sell at a loss and will not buy again. not all investors are able to implement the DCA method, you must be able to have all of the above, then you can be called successful in investing.