I believe the concept of HODLing Bitcoin is nearly as old as Bitcoin itself with the fundamental reason and hope that it will increase more in value over the years. Although several persons are entitled to there own reasons for HODLing, could it be that some persons HODL because they are waiting for the perfect time or they are too scared to sell or lose a percentage of their Bitcoin?
It is not like people are scared to sell their Bitcoin. The reason they are holding Bitcoin for a long term and not selling some part of it is because they know that Bitcoin is a valuable assets and can skyrocket in the future so they want to make more money than the current amount they will make it they sell now.
Everybody have the right to hold or yo sell their Bitcoin, selling their Bitcoin is based on their own will but holding Bitcoin for long term will profit more than short term.