Yes it is possible to cure jerky for too long.
When you cure the jerky too long the jerky becomes more salty and then if the jerky has cured way too long then the jerky will be way too salty and you'd likely want to throw it out instead of eating it.
Jerky should only need to cure for 6 hours to 24 hours.
If you allow the jerky to cure longer than 24 hours then the jerky starts getting more salty.
Jerky is expensive because the jerky takes more meat to make then it actually looks like.
The jerky also has to go through a curing process which takes time and money so the jerky has to be more expensive than other meats because of the extra costs.
With beef jerky the beef that is used to make beef jerky is about 60 percent water content so when the beef is dehydrated the beef gets smaller.
So it takes more beef to make the amount of jerky that is needed.
To make 1 lb of beef jerky it takes about 2.5 lbs of beef to make the 1 lb of beef jerky.