Meta's message to investors: The AI spending will continue until returns improve.Investors' response: No thanks.AI spend was the big focus during Meta's Q2 earnings report. And the pitch wasn't convincing enough to stop an after-hours selloff. Meta was happy to credit AI with helping its advertising business (its bread and butter) rise 27%. And it wasn't just pure growth. Ad impressions grew 14%, while the average price per ad climbed 12%.There's just one catch. Meta is still spending an incredible amount — ...