No! Bitcoin isn't leading the internet based transaction volume! Paypal does! Bitcoin's market cap is 165 billion USD right at this moment whereas PayPal churned out 172 billion USD alone in 2nd quarter of 2019! Bitcoin is still 7 billion USD less! Reference is given below,

https://www.businessinsider.com/venmo-played-key-role-growing-paypals-tpv-2019-7?IR=T

Bitcoin surely turning the tide slowly, but it has yet to cover the road!