Eklavya approached Dronacharya the teacher of this art and was rejected assertively although politely. He did not have the background or any future responsibilities that could be meted out to him for him to learn the art of Dhanurvidya (Archery). In today's World its like teaching and giving capabilities of building a Nuclear bomb to a person or a nation not responsible enough with not much stake to lose in case of its wrongful use. With no prior context, no history of schooling and no background required to step up would also drain and unnecessarily diversions that will be caused by including him in the class, Dronacharya thought. Eklavya's passion and his hidden and unpolished talent was ignored, there was no need for a follow up.
But Eklavya was Eklavya he persisted. He knew he did not belong to that club but knew he belongs to that art. He started stalking the teacher to his class and started watching and learning by hiding under thick foliage. Have you downloaded a copyrighted material an exclusive content that you need to pay to use? Have you been using a software that requires a license to use? Eklavya was not doing it to challenge the others, he was using to gain the knowledge he was interested in.
Eklavya did not have the quality of bow and arrows required to implement the knowledge he was gaining but what he was able to do with a simple hand made archery that many Princesses could not do in the club with their sophisticated arms except one Arjun. Eklavya would go back practice all day all night what he saw Arjun do. He remembered every intricacies that Dronacharya talked about that many simply ignored in the class that he did not. Eklavya was learning what lies in the heart of that art, the best practices, how to make the best use of it, how to achieve your goal with minimal resources than to shoot to kill an ant. Eklavya was indirectly challenging Arjun. To learn how to avoid a war and keep your interests intact makes you a better fighter than those who know how to use Guns. Eklavya became a much better Archer than all and he gained that not working in a team, not getting anyother brain to pick - he did it by watching and practicing. He would fail to use the sophisticated arms but knew how to hit the target with his simple ones. He filled the gaps in his knowledge with better designs. He did not need the strength to stop an incoming train, he knew to build a road that does not intersect the path of it.
Cheating is always caught sooner or later. Eklavya was caught by Dronacharya when he filled the mouth of a dog with arrows just enough just deep enough to not hurt the dog but make him stop barking. Such a precision was only possible by Arjun and there can not be another Arjun. Whoever is that precise and not a brother of Arjun could potentially pose a threat to him later. Dronacharya could not trust Eklavya's loyalty. Indirect may be he did learn from him and had to pay Dronacharya said and he asked Eklavya's right thumb as his fee. He decapitated Eklavya for ever.
Eklavya was rejected. He was rejected because he was the son of a Father who worked for a King opposing Krishna the friend and spiritual Guru of Arjun. Dronacharya though was impressed by Eklavya's desire to learn but his background was not in line with the interests of Arjun. Eklavya even without a thumb remained a potent Archer better than many but later killed in a battle with Krishna. Later Arjun and his cousin brothers split and had a war what is known as Mahabharath one of the most devastating war the World had seen. Arjun won, his character won, his piousness won - but there was no Eklavya to challenge him.