because you shouldn't forget that the main purpose of bitcoin is keeping funds and no one obliges you to spend your investments
False, bitcoin was created as an alternative currency to the fiat systems, others are just additional benefit you get from believing in the technology. The asset side of bitcoin is very vital but shouldn't be be prioritize as the main idea behind the creation of bitcoin. If we want adoption we should encourage the use of the currency for our day to day needs although that doesn't mean holders aren't supporting this course.
Don't forget with the fiat system, you have funds allocated for savings, investment etc and also have those allocated for spending, same can be said about bitcoin. The reason behind the hold ideology has to be for those going into investing, instead of trying to outsmart the market every now and then by trading for profits, it's most advisable to just buy and hold.