The vast majority of extensions on Twitch do not make significant income with bits, and even those running on the largest channels on Twitch do not see much in the way of bits transactions. Most streamers, and a good portion of viewers, know that the broadcaster only takes an 80% cut of Extension transactions so it’s a VERY poor way to support the broadcaster compared to just tipping them or cheering the bits.
Extension Monetization is largely lots of very small transactions, usually less than 250 but most less than 100.