Compared to other fish, bettas are not particularly long-lived. Even within this parameter, many die premature deaths due to misinformation about betta bowls. One reason for short life span in your tank is people prefer buying a male betta that has full fin growth, Betta lovers get the long, lush fins they want, but they're already a year or older when you get it. Some people who have kept very old bettas, nine years or more, attribute their fish's longevity to their practice of gently chasing their fish around the tank everyday for exercise. Bettas do not live very long. Although there are exceptions, most bettas die within the first four years.
Eventually your betta will die, whether it was natural or disease and uncleanness.
How To Tell Your Betta is Growing Old[]
At a certain age, a betta will slowly shrivel up (Note: This is for uncared for bettas. Healthy bettas may age differently). It will become small and not as attractive, like an aging person. Your betta's fins may clamp and when it sees its reflection, its colors won't brighten up.