It takes discipline to be a long term investor, it's not everybody that can be diligent enough to be taking money off there discretionary funds to be buying Bitcoin for many years. There will always be distractions along the way like when price hits a new ATH. They'll be tempted to sell forgetting that Bitcoin has the potentials to always reach new ATH.
your are very correct, because it's not an easy thing to be a long term bitcoin investor, it takes discipline, patent and commitment to be a long term bitcoin investor. And just as you said above it's not everybody that will be willing and disciplined enough to be investing in bitcoin consistently with their discretionary income for 4 to 10 years or more without being tempted to sell off their bitcoin investment in other to take profits. But my advise is no matter the temptation that will come our ways during the long run of our bitcoin holding, we should always try as much as possible to tell ourselves that bitcoin is a coin full of potentials.