one way for bitcoin to have a stable value is to legalize bitcoin into a legitimate currency that can be used as a means of transaction in all countries. and crypto currencies are not used as trading tools such as stocks. so the crypto currency has a fixed value and does not depend on trade market demand.
for now, I think it's very difficult to do it. maybe a regulation will help. but, basically, bitcoin is indeed very difficult to stabilize, there is even a difference of a few dollars a day in the increase or decrease. even more so when demand is overwhelming.