Adam was adamant about opening his poison chakra cause he had found a scripture in his house which was thrown away after his parents annihilated the poison clan.
The reason Adam parents hated poison clan is that they make small insects as their familiars and load them with poison which is extremely potent and make assassinations.
Even Adam's parents had hard time dealing with the Poison clan, as they always explore and research all the possible poisons to create a poison that could kill even a god state warrior.
After annihilating the poison clan, his parents threw away all their scriptures including their clans techniques and skills. Adam found the incredible use of this techniques and by hearted them, so that if he can open a poison chakra he could use this technique.
His parents always objected it, but he was reading it regardless.
Then one day his parents made him to promise not to practice poison arts as it's not humane.
But now for the sake of revenge Adam was ready to let go of his humanity.
That's how he is determined about the revenge.
As the time flows slow in the abyss, he can cultivate and practice slowly and he put a target of 2 years which is 200 years in abyss into opening all his chakras.
Adam then learnt the basic poison arts
poison mist, poison blood .
Then he went on to hunt low level beasts with his new found power.
He killed all the low level beasts with help of poison.
And he was ready to open his next chakra
He went to Kevin and asked him to open his Dark chakra.