I think the combination of many smaller and unique factors - to name but a few - the “never read 1000 page EULA” incentivising users to just click through blindly, lax restrictions regarding privacy policies and terms of service being comprehensible to the lay person, data storage being cheap incentivising collection, advertisers taking advantage of new technology and making themselves impossibly wealthy.
Individually they’re not so noticeable, but together they hammer at the wedge, driving us towards an opaque hellscape