Because wBTC has Infinity more utility then native BTC. And their digital gold narrative could be wiped over night by Eth + alts tokenizing Actual real gold, which funnily enough would be cheaper, faster, and more divisible then "Digital gold", you can even buy coffee with it. Pick related is Fees on L2, and yes they are integrating L2s so much that you soon won't even be able to tell you are using a L2.