Afaik breaking a 128-bit ECC key does not require brute-forcing 2^128 keys but rather computing 1 difficult problem on a 128-bit input.

Breaking e.g. AES key of n bits requires you to try 2^n combinations, but the actual computation per key is very fast.

[1] https://crypto.stackexchange.com/questions/13249/why-can-ecc...