A lot considering the reader in most not all but most cases are bias towards the Mc of the story they are reading since we see it from mc's perspective
It takes some good skills to write a messed up character in a way that hooks people even when they do outright evil things, so I'd say it'd be a 50/50 chance. He seems annoying to me though, so I can't see him being the type of "you love to hate them" character atm.
If the character is annoying whether mc or that lee hansol, audience most of the time get annoyed too. Just like some other manwhas where I found the mc annoying, stupid or heartless and even semes where to get rid of their toxicness the artist had to make seme regret of everything so audience who were not happy with the character could be satisfied
This white boy Lee hansol even if was a clone/ test subject, he is very annoying from the beginning for many audience to not have sympathy for him, like his character literally represents those btchy mistress to begin with who try to take other's partner for their own gain. If he realises his mistake and starts to change himself for the better, I'm sure many audience who even like toxic mls just coz they apologise or had an redemption arc will like him too. But I don't think his character gonna be improve from a villian to a good smth piece
I wonder if the story was told in favor of lee hansol, or lee hansol was made into an attractive top instead of the current couple, how different would the audience opinion of him differs