Remember there are set of people that invest From thier discretionary income yet they don't have peace of mind, they still panick during the dip. So this is just all about discipline, You can have a discretionary income to invest in but if you're not discipline you can't stay focused as you may be tempted to sell off your holdings some day due to pressure so as a newbie who is about getting started with bitcoin investment you need to be discipline. Discipline i mean in terms of sticking to your decision once you decide never to tempter your bitcoin investment for any reason then you Stick to the decision let your yes be yes not just after making a decision maybe due to pressure you just decided to sell your holdings no, you just need to stay discipline no matter what.
Yes you are right. Having a discretionary income and investing from there, doesn't make one safe from volatility and price fluctuation. Since investors only panicking when the price is moving towards the opposite direction they had in mind. My conclusion, is that they dont know the true definition of discretionary income, because just like the saying "invest what you can afford to lose". Your discretionary income should be a comfortable percentage that you can afford to lose that amount in a week by risking it.