Look at the list. Dwight Howard anyone? Signed 3-yr/$70.5M deal on Tuesday, July 12, 2016
Dirk signed this: Signed 2-yr/$50M deal on Saturday, July 23, 2016. Might be worth half if that at this point...maybe
Dwayne Wade: Signed 2-yr/$47M deal on Friday, July 15, 2016
Lots of others over the years. Anyone who gives Carmelo a big contract is overpaying.
Now, young kids coming in...no, a GM isn't paying for that, if that's what you mean. But there have long been great players with less name recognition than other great players, and they tend to be paid less. It happens in every sport. Names sell tickets and merchandise.