Google was the first example I thought of, because they were founded in 1998, solidly before the dotcom crash. They survived because they hoarded data.
My point was that every company going into the bubble thought they had a product they could monetize, but virtually all of them failed in favor of just hoarding everyone's data. Amazon and eBay were competing for ecomerce supremacy, but now even they are just privacy violators for various reasons (amazon via AWS and Alexa, eBay in the interest of detecting malicious account behaviour).
MySpace is an example of another unsustainable social media model in the vein of many dotcom era services. They died out as soon as Facebook realized they could hoard everyone's data.
All roads lead to privacy nightmares. It's the fossil fuel of the internet, and enshitification is the climate change.