How is the Draft actually better?

So as I understood draft is to make all teams basically fair unlike how in football the riches teams gets the best players I understand this

But if this is the case then how is it possible for teams to sell there draft picks because by the very nature that would created an unbalanced

And there isn't even a limit to how many first round pick a team can have so for 5 years strait one team can get first round pics

I don't understand how this is in anyway fair