Is it reasonable that my 2014 Hyundai Accent with 105000 miles on it would need a catalytic converter? What am i doing wrong?
That is extremely early for a catalytic converter to need replacement.
If the engine consumes a lot of oil, that might explain it.
Is it reasonable?
No.
Is it possible ?
Yes.
If the catalytic converter isn’t physically damaged, I suggest trying this first before replacing.
https://www.walmart.com/ip/Cataclean-Exhaust-Fuel-System-Cleaner-16-oz/135378546
Tester
How do you know the cat is bad? Might it be the oxygen sensor(s)?
Are you in California?
Yes, it is certainly possibly.
You might try taking it to a Hyundai dealer. Most of the exhaust components have an 8 year factory warranty on them. Being a 2014 model, you might just slip into a warranty replacement.