AskHistorians

A unit of spearmen works together to stab you from a further reach than you can respond with a sword. I think you also overestimate the ease with which you could chop a spear. Designs differed, but a Greek dory was about 2 inches in diameter. Try taking a whack at the wooden shaft of a shovel some time and see if you get it in one go. Remember that in combat if you were doing this, the person with the spear and the rest of the front rank would also be trying to stab you rather than standing still like polite mannequins.

A formation unit purely of sword-using infantry against spears would be pushed as the spears could kill the sword-users, while at best the sword-users could damage some of the spears but wouldn't get close enough to harm any of the spearmen. The spear unit with multiple ranks of usable spears could keep going even if a few spears were damaged.

Some sort of skirmishing formation of sword-users would be in even worse shape, as they'd be overwhelmed by a formation and as light moving skirmishers would likely not have full sized shields so if archers were involved would be easy pickings.

Swords in the Greek ancient world were used for close in fighting once the initial contact between formations had been made or if the quarters were otherwise impractical for spears.

You get stabbed first

Because they're actively attempting to stab you and you're no Achilles. It's hard wood that's not braced against a surface, you're using a bronze sword, and a lot of people are attempting to stab you.

Go sharpen a kitchen knife and try to cut a longish wooden dowel of spear diameter while you hold it in the air in one hand.

Go get a 2-5.5m long x 2cm Ø hardwood pole and see how much it wiggles

Add in the fact that you don't have many skilled professional soldiers and depending on period they're probably on horseback, archers, or some other role beyond the classic hero archetype of Jet Li or Achilles.

And you have to keep in mind, a lone guy with a long spear is going to struggle, much in the same way that a cavalry rider is going to really struggle fighting on a bridge. By the time you're in that position you're losing. Spears are best used in formation, Ideally a line of spearmen with the row or two behind them stabbing over their shoulders. Short spears and javelins can act as a compromise as seen in roman legions.

Ultimately though there's a reason anti spear troops became a major part of medieval warfare. Pikes are cheap, easy, and good at killing knights

You were originally asking why spears hung on so long as a military weapon. Battles were not one on one duels. To ignore this seems to be fishing for some kind of answer that intentionally ignores the historical context.

Kung fu movies aren't real life. This is closer, and the sword loses a lot. You might dodge some thrusts, but out won't be able to close and get an attack off most times. https://youtu.be/igaQww59NY0