Maybe a bit gets flipped every 24 hours but yeah cosmic rays don't just erase a whole drive... bit of a case of telephone here tho, just relaying a moment of inspiration.
DRAM/SRAM/Flash bits and CMOS triggers flipped (not all at once, random). Magnetic media is much more resistant, but in almost all HDDs using classic CPU (and DRAM cache), which are affected by cosmic rays, so info corrupted when travel from HDD surface to computer motherboard.
