The price of 1 bitcoin in inflation-adjusted USD, starting from Jan 3rd 2009. All price adjustments are based on the current purchasing power of the dollar according to the consumer price index, and comparing to 2009 on the day the genesis block was mined.
You can disregard the invisible Visa symbol. It's a dirty trick that allows me to merge both of the Bitcoin-related price scales without merging in CPI , while also keeping inflation data back to the 2009 genesis block. This is because BLX data only starts in July 2010 and having it as the primary symbol would have suppressed inflation data prior to that. I picked Visa simply because its IPO happened shortly before the first Bitcoin block was mined, so it removes most of CPI's irrelevant data dating back to 1947. Unfortunately I couldn't completely hide it (you can still see its value in the price scale if you zoom out a lot). Additionally, the chart skips the days on which Visa wasn't trading (but that shouldn't matter on a large scale).
Drag the time/price scale to adjust data. Double-click the price scale to auto-fit vertically.