In Todays world,
Rich Person= King
Son of rich person= Prince
Lets assume there is a finest math's teacher in the city ,
Rich person would always want his son to be the much better scholar than himself, or maybe best.
wouldn't he hire that best math's teacher in the town,
whereas the poor kid had to learn everything from the government run schools and probably himself,
but the poor kid is at par with the rich kid or maybe more intelligent,
According to you, that you stated above , you want the rich Person to adopt that poor kid because he is more intelligent than his kid without resources,
That's absurd,
Wouldn't the rich person try hard apply his best force towards his son to become the best,
Rather than adopting the poor kid,
Dharm or casteism has nothing to do with both the kids and even rich person, those are just the lack basic amenities and efficient amenities.
So Pandava king adopting Eklavkya over his own son Arjuna is absurd to think even in todays world.