Direct to consumer or DTC was hot as a firecracker a few years ago, as brands like Allbirds, Warby Parker, Bonobos and Stitch Fix, among others, flew high by bypassing the retail channel and going all in on digital. Now the tide seems to be turning a bit as many of these marquee DTC brands have stumbled in terms of sales and profit margin. What’s going on here? What headwinds have they run into, and how do they need to adjust? Alex Kantrowitz, host of the Big Technology podcast, author of “Always Day One” and a contributor to CNBC, helps us break it down.