Where do you think they threw the grounds?
Either A) a compost heap or B) a landfill, neither one of which should see anything going into the ocean unless something's gone very wrong with the whole process. Assuming you dump your coffee grounds into a garbage disposal or flush them down your toilet or whatever asinine thing that still shouldn't lead to much of anything making it into the ocean unless we're dumping raw sewage into the Pacific now...
The harsh truth about old people is that supply exceeds demand. For example in the US there are now only about 2 workers paying into Social Security for each retiree, much lower than what was intended for the system to work.
The system would almost certainly have remained solvent while this structural issue sorted itself out (read:the baby boomers all died off) if the congress-critters were able to resist keeping their greedy little fingers out of it's fund for more than five minutes.
In any event though, anti-senescence research could actually fix this in the long term. If we can start eliminating the negative effects of aging people won't need to retire as early.
"They that can give up essential liberty to obtain a little temporary saftey deserve neither liberty not saftey." -- Benjamin Franklin, 1759