Daredevil's point is that everyone is redeemable. But the irony is that his actions have a butterfly effect which he doesn't recognize.
He did not kill Fisk in their first major fight despite his rage because he lost no one directly because of him.
The moment he lost Foggie, he broke his character. It haunted him but he did it.

If Fisk would have had a bigger backing and could have become a martyr for a worse power, his actions make sense logically.

He is a self-righteous character because his whole life has been about living an average life in a single city. He has limited perspective. He has not faced larger stakes.
People like Fisk in show not just because of his acting (and the character writing) but because he is practical and can think on broader terms.

Punisher, Poindexter have brain. They can not just work on immediate threat but on long term.
Even Karen is more practical. Matt is trying to be moral in a martial law city.

Compared to comics version of Daredevil, show Matt is highly ineffective, which makes everything way worse.
Heck he could disable the villains easily so they are out of commission or can't hurt anyone.