And google didn't fail to diversify for a lack of trying !!! It's just that ads continued growing faster than anything else could catch up.

Either way, it’s a zero sum game. The productive sectors of society (businesses with goods and services) spend on advertising to attract customers away from each other. The majority who don’t have massive budgets for optimizing soon realize the ROI is negative on ad spend, and stop. Same as traders who get liquidated after trying futures.