I understand your opinion. You are comparing how long the fish had lived with you to if it was with someone else who might be doing a worse job.
That someone at aquarium store told you one true fact, "those fish don't live long in a bowl". It is the same as “Those humans do not live long in concentration camps”. This fact is the truth because a fish bowl is too small for fish, and most beginners not only have no filter but they also do not change water as a part of regular maintenance.
A fish will die faster in a bowl without a filter and without regular water change. A fish will die slower in a bowl without a filter but with water change. It does not change the fact both are the incorrect ways to keep a fish in captivity.  All fish in captivity require a filter system running 24/7 in order to keep the aquarium nitrogen cycle going.
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