Same as eggs… if enough people believe other people will want to buy it for a dollar more than they paid, they will pay the asking price. When supply is scarce that drives the price up.

Check the y axis. Each horizontal tick mark on the graph represents $2.50, which is 0.13% of the price of one (share of?) etherum in your second graph, and instead of the y axis starting at $0, it start at about $1865.00. You're super zoomed in, making what are actually very small price changes look very large

For the most part, Crypto assets have no real value. They can be used as a currency, but that's infrequent at this point, and really it's now just a speculative asset.

In other words, Ethereum's (and other Cryptos) value is based almost entirely upon how much people think someone else will pay in the future.

If they think the price will go up, then they will buy. If they think the price will go down, then they will sell.

Because of this, any shred of evidence that could predict the perceived value going up or down can cause a huge shift in the market. Most likely a news article was released, or someone Tweeted something, that made people think the price could change.

It's all pump and dump. Look at Elon with Doge Coin. Look at Trump with his dumbass NFT "cards." Most initial coin offerings are just pump and dump schemes, and they're often based on etherium.