Someone posted the image on the left and I noticed this fit Ethereums USD chart exactly. Like... exactly!
If the red chart on the left is the "value of all public technology companies" this does seem to fit the idea that an industry is represented by Ethereum.
So then Bitcoin doesn't behave like many expect it to because it represents the ENTIRE blockchain/cryptocurrency sector (such as the internet itself, telecommunications ) and therefore we would expect the chart to form something more similar to that than any single company or stock. These tend to go straight up, more or less. Seen from this perspective Bitcoins charts make a lot more sense.
This also goes some ways to explain the insane prices of crypto compared to the "real world". In the real world you're not able to invest in an entire system this way.