Because of Dhrtarastra's bodily attachment he could not hear Vidura's repeatedly given good instructions. Dhrtarastra was an elevated person, but because of the influence of his son, Duryodhana, and by the influence of Sakuni, he acted wrongly. Vidura was so much respected that Bhismadeva, who was very much his senior, consulted him. Vidura recommended the Gandhari marry Dhrtarastra, Bhisma agreed, and Sakuni drove Gandhari and Dhrtarastra to Dhrtarastra's home after the marriage. Later, after Pandu died untimely and his wife, Madri, entered his funeral pyre, Duryodhana and his brothers harassed the Pandavas. Krishna , the eternal well-wisher of his devotees, the Pandavas, was concerned and sent Akrura to investigate the situation in Hastinapura. Kunti, her eyes full of tears, inquired from Akrura if Krishna had plans to protect the Pandavas, and he and Vidura reassured her. After observing the situation for three months, Akrura advised Dhrtarastra:
(1) Do not act on the platform of the ignorant bodily conception of life by differentiating between the sons of Pandu and your own sons. Each life one has a different set of sons, so one should not be so attached to “one's own.”
(2) You should act out of virtue.
Dhrtarastra praised the wise and ambrosial words of Akrura but said that due to attachment to his sons those words could not remain in his heart and he could not carry them out. He was content to let whatever would happen as a result of that happen as ordained by fate. This failure to take responsibility for his actions resulted in his downfall, and we must be careful not to helplessly act according to our material attachments, neglecting higher principles, or that will also be our downfall.
That Dhrtarastra wanted a kingdom for his sons was not the problem. Dhruva also wanted a kingdom, but Dhruva went about it in the proper way, by asking the sage Narada how he could rightfully obtain it. Dhrtarastra, however, cast righteousness aside to further his ambitions and thus his sons were destroyed. Because Dhruva was respectful to Krishna and his devotee Narada, his ambition was achieved, but because Dhrtarastra disrespected Krishna and his devotees, the Pandavas, his party was destroyed.
Dhrtarastra later reflected on Akrura's advice and inquired from Bhisma and Vidura about their opinion. He decided that since Yudhisthira deserved the kingdom and the citizens wanted him to be king, he would perform a ceremony making Yudhisthira the incumbent king.
Meanwhile Duryodhana met with Karna and Sakuni. Karna thought that they should fight the Pandavas and take the kingdom rightfully by conquering them, but Sakuni, seeing how the Pandavas easily conquered King Drupada, who had previously conquered Duryodhana's party, was afraid they would lose and thus wanted to use unfair means to deprive them of the kingdom. Outraged, Karna left the meeting, and Sakuni revealed to Duryodhana a nefarious plan to get the Pandavas out of Hastinapura and then kill them, explaining how they could do this without objections by Bhisma and Dronacarya.
Dhrtarastra, because of his sons ambitions, worried what they would think of him making Yudhisthira the incumbent king, and thus he consulted Sakuni, who engaged a materialistic so-called brahmana to advise Dhrtarastra to kill the Pandavas. King Pandu had taken good care of his blind elder brother Dhrtarastra, and the thought of killing Pandu's sons was not at all palatable to him. However, Duryodhana knew how attached Dhrtarastra was to himself, and thus he threatened to commit suicide if Yudhisthira became king. He further argued that Dhrtarastra and all his sons would have no position if Yudhisthira became king and the whole situation would be miserable for them. In this way, Dhrtarastra's mind was changed, and he heard the plans Sakuni made for getting rid of the Pandavas, and let them be carried out.
The moral of the story is that because the Pandavas took shelter of Krishna, they were not affected by bad association, but because Dhrtarastra had no such shelter he became a victim of bad association and was destroyed. Actually we can always trace destruction to some bad association in the past. Thus we should always follow the example of the Pandavas and escape bad association by taking shelter of Krishna.