Wondering why people upgrade when old gpu work fine?

With all these new GPUs costing an arm and a leg, why do people feel the need to upgrade? A GTX 980 can still run a huge number of games perfectly fine, just as an RTX 2080 handles almost any modern title without issue. Even a GTX 1080 remains more than capable. So why keep spending hundreds—or even thousands—on incremental improvements when older hardware still delivers solid performance for most gamers?