Several spot Bitcoin (CRYPTO: BTC) ETF issuers, such as BlackRock Inc (NASDAQ: BLK), Ark Invest, VanEck and Grayscale, are launching TV commercials advertising their Bitcoin exchange-traded funds, which attracted over $4 billion in trading volume on the first trading day. Bitcoin ETF Marketing Battle Begins The hard work for investment funds has only just begun. The evidence of that is in the flurry of TV commercial releases advertising the new Bitcoin ETFs that have been making the rounds on social media. They welcome Bitcoin on the big stage of asset classes as the funds start their marketin…