Here is the scenario

Joe User is about 75 meters from his Wireless Access Point/Gateway that has a range of 100 meters.
Attacker is about 50 meters from the wireless Access Point/Gateway on the side opposite Joe User.

Both Joe and Attacker are within range of the access point. However, Joe and Attacker are 125 meters from each other.

It would be possible for Attacker to break into/attack the access point... but he would not be able to break into/attack Joe User because he is out of range.

The reason I say this is... the only time traffic goes through the gateway is if it is leaving the local network. Only goes through the gateway if it going out to the internet. Or, since the Wireless Access Point/Gateway is providing the link to the network... would it forward the traffic between Joe User and Attacker?

I'm not on a wireless network at the moment to test this...

I'll attach a pic to give a visual representation of my scenario.