Bitcoin has been around for less than twenty years. Since then it has seen massive deflationary periods (when the relative value rises, like up until a month ago), and massive inflationary periods (when the value drops) In 2018 bitcoin had an "inflation" rate of roughly 500% (meaning that at the beginning of 2018 you could buy a basket of goods with an equivalent value of $13.5k USD, at the end of the year you had to spend 500% more bitcoin to get the exact same basket of goods. Meanwhile you only had to spend 2-3% more USD to get those same goods)

The fact that there aren't bitcoin loans is proof that it is not a viable store of value.