The 3-point shot is a standard part of the normal, every day NBA game. Regulation hoop and height, same line distance that players are used to every game, etc.
The chest pass part of the challenge, while a skill that NBA players posess, is an arbitrary distance into an arbitrary goal size. They don't set one of those up at every practice to have players run through a "chest pass into a small hole 20±feet away" drill on a daily basis. It is just not a normal drill or repeatable skill that players have. It's like one of those basketball shot games at the county fair. Smaller than normal hoop size and it is much higher than a normal hoop, etc. Also, during a game, on the other end of a chest pass is a player with hands and arms that can gather a slightly errant pass.
I agree completely that a set number of attempts is fine to impart a time delay for the player that misses on the chest pass. We can argue 3 or 5 or whatever, but almost all the passes I saw (didn't watch the whole thing) were very close to the hole. It's not like they were my 78 year old dad trying to shoot a blindfolded half court shot. The time delay for missed shots was penalty enough.
The three point shot at the end should be a final equalizer. Keep shooting until someone makes the head-to-head competition end.