The difficulty of the problem is variable. Some variants of the problem are trivial to solve, while others can be proven to have a higher computational complexity. It is precisely those cyclical elliptical curve subgroups are chosen for public key cryptography.

And the reason discrete logs are chosen for cryptography is because the inverse function is trivial and therefore the elliptical curve subgroups have an asymmetric property of easy to verify, hard to solve.

That is why it is easy to verify a Nostr post is legitimate with a public key, but near impossible to guess a private key with just the public key.

And since you can mathematically prove the average computational complexity of the EC groups, you don't have to assume that the discrete log problems in cryptographic systems are difficult.