For lack of data, they generate random bytes collected on every mouse movement on every page, and every packet that moves through their network. It doesn’t tell them anything because the only information that means anything is who clicks that one button on their checkout page after filling out the form with their information or that one request that breaches their system.
That’s why big data is synonymous with meaningless charts on pointless dashboards sold to marketing and security managers who never look at them anyway
It’s like tracking the wind and humidity and temperature and barometer data every tenth of a second every square meter.
It won’t help you predict the weather any better than stepping outside and looking at the sky a couple times a day.