please tell me how i can get that much gold to finish the build.

i really hate how some carries never realize the work their support is really doing. I had a saw who stayed in lane the whole time and never rotated. he was building wp but when ever a fight started he waits to the middle of the fight to use his A so he get no health regain and he is locked in place so everyone targets him. i popped atlas and crucible and fountain for him but he still died because ringo had double monocles. but what I hate is he kept pinning me question marks the whole game....