When bitcoin is volatile, the only people who want to hold it are investors and traders and everyone else wants to dump it like a hot potato. When bitcoin is stable, it is more attractive to use as a savings account, unit of account, or for a merchant to actually accept it, rather than immediately dumping for cash. Stability increases hoarding and business use. Ironically this will then eventually make the value go up, removing the stability and starting the cycle all over again - until bitcoin does enough jagged lines to reach its final price discovery.