I don't disagree with what you are saying; however, it does seem that you skipped the most important consideration, which is investing within the boundaries of your discretionary income..., which also should mean that the discretionary income that you use is income that you don't need for 4-10 years or longer.. which means that it is also money that you are willing to completely lose in the event that bitcoin were to go down rather than UP.
Under normal circumstances, investing the amount of money that you can put away for such a long duration of time like 4-10 years as you mentioned, but the crisis most time arise from situations where the investor put down money that they need for immidate expenses into investing in bitcoin and at that they will be under pressure when bitcoin noise dive backwards, this are the set of bitcoin investors that are always at pressure to see bitcoin rise immediately after they investment, but bitcoin doesn't work that way and even though sometimes bitcoin can give an immediate profits on investment, that is not a guarantee for anyone to invest the amount of money that they can not risk to lose or look away from for a long time to see the investment appreciate in it value with time.
Sure no one invests in bitcoin or in any other kind of an investment with an intention of losing money, yet part of the way of assuring an ability to stick with an investment through the ups and the downs is to use extra money that you don't need for expenses.
For bitcoin unlike other investment where it loses can result into 100% lost of investment, bitcoin only take time, that is even though you at lose at the moment, if you continue holding to your bitcoin accumulated holdings, with time , the value will increase, recover and you be in profits again, so in bitcoin time is very important and what differentiates the loser from gainers in bitcoin investment is the amount of time they both are willing to wait to see they expected profits comes, but the weak hands won't accept the principle of waiting for bitcoin to recover the rush to sell when the market goes against them, that is why they lose they invested capital.