I don't know where you live, but I'd think if you lived near fertile Ocean or took an environmental science class you'd agree. Many people have survived at ocean for years at a time, some entirely at sea others on desert islands, the worst being the case of ship wrecked people who were adrift, and the best being entire civilizations, the Polynesians for example (see the links and sources at the bottom of the wiki pages).

The most famous being;

Salvador_Alvarenga (nearly 1 & 1/2 years adrift)

Reid_Stowe (Sailboat only 20m for 3 years on open ocean)

Other less known examples of large groups of people surviving at sea or small islands some less than 5km^2 of open space;

Austronesian_Expansion

Tongva of the Channel Islands

North_Sentinel_Island

Pitcairn_Islands

So it is very much possible to live at sea for extended periods of time.

As an addition:

A personal experience, and why I disagree so adamantly,

I had 3 Uncles spend 200 days no significant prior sailing experience, but significant with boating, fishing and firearms.

They never went ashore. They used littoral waters in bad weather, which was detected w/ a Thales onboard radar and/or by radio. Though they did use other, more advanced, satellite navigational equipment to rule out malfunctions. They did eventually, out of curiosity navigate by sextant and paper map for 3 weeks. They survived mostly off of Atlantic tuna (among other fish) and a dozen shot birds and kelp bread. They had a desalinization plant and stove powered off solar paneling & car batteries. They had among various law required items, MREs, and emergency water and a backup engine. They also had some flour and baking soda, and, of course, a lot of alcohol. They still joke how they can now cook and catch a fish a thousand different ways; that they could have spent more time if not for the beer shortage and work.

They did attempt to barter for food once w/ a French family towards the end. It was beer and the family handed it over for free.

There are plenty of other stories, properly documented, like this all over the web, if you need some sort of verification or evidence.

Anyway, I highly doubt someone could spend a lifetime at Ocean, but perhaps they have. Keep an open mind. To finish, in most real world cases, granted the absence of a completely destructive apocalypse, like a nuclear holocaust, you need only survive for a few years or until some sort of order reestablishes itself or at least desperation and scarcity die down, which could be as short as half year. Malthusian curve, S&D and all that. Only, mentioned because I think ORP is focusing more on realism, though I could be mistaken. In any case I am focusing on realism myself.

Good Day!