I think you're the one that is getting yourself confused here, I don't mean to dispute on the fact that investing from your discretionary income means you're Investing with peace of mind but even as that one also need to be discipline so as to enable you stay focused regardless the ups and downs of the market. Because alot of people have been investing from their discretionary income yet they don't feel comfortable when there is a little drop in the value of bitcoin simply because they are not well discipline so when investing from your discretionary income is also advised to apply self discipline this would help you to stay focused no matter anything.

This is how important for having a emergency fund aside from considering to have discretionary income to use for investment. Since they can make sure that they have some funds to use for their special needs and they don't need to touch their investment and sell it more earlier on the timeline they set.

If they always think about investment and use all everything they have for this purposes then provably that they might suffer on rainy days season in their life. Since this situation could make them fail and its so bad if when they sell because they don't have a choice the current market situation experiences a bearish run, with that they have good chance that they might lose some amount and that completely waste of time and effort for them.