I spent years working on system handling 50+PB/day of logs. No database or ELK can handle that, and even if it did it would be prohibitively expensive.
A mighty 400 GB/s: i.e. much less than the > 50 PB/day of logs the other person mentioned;
1600 hours of SD video per second: i.e. about 1-2 million concurrent HD streams, or much less than the amount actually served by YouTube.
IBM Summit "world's most powerful supercomputer": < 5000 nodes, i.e. much below the median cell size described in the 2015 Borg paper. Summit is a respectable computer but it would get lost in a corner of a FAANG datacenter.
Otherwise the tape alone to store it on would exceed their total operating budget in a day, so they have to be a bit clever about it.
not quite as big a difference
Anyway, GPDR requires you to have a purpose for any log that contains any IP address. Keeping logs for undefined purposes and unlimited time frames is not ok any more.