Can Advertising Fund Free AI? Evidence from ChatGPT's Advertising Rollout

This working paper uses data from 1,898 online shops to test whether advertising can fund free AI access during ChatGPT's staggered international rollout, with the EU untreated. Ads moderately reduced organic ChatGPT referral volume (about 6–8%) but not conversion, while paid ChatGPT visits generated $0.89 revenue per session versus $2.45 for paid Google Search, a 64% shortfall. The authors conclude current ad performance is not sufficient to finance free access costs.