Why I used to prefer permissive licenses and now favor copyleft

The author, Vitalik Buterin, argues that copyleft licenses now deserve preference over permissive ones, reversing his earlier stance. He previously favored permissive licensing, using the WTFPL for his blog, to maximize adoption and to avoid copyright altogether. His change rests on three points: open source is now mainstream, crypto has become more competitive so openness can no longer be assumed, and economies of scale risk power imbalances that copyleft can counter by encouraging diffusion of progress. He concludes that projects choosing permissive licenses 15 years ago should at least consider copyleft today.