Im going to be careful about how I word this Andy... Maybe Gary has thought this through more judiciously than you think, and maybe you haven't listened to him as carefully as YOU think you have. He has talked about how you can catch "multimillionaire runners" through taxation on their UK assets.
Don't worry, I'm not ideologically bound, nor offended by disagreement. On the other hand I have worked in this sector (I led the team that built the UK's first online bank), and have watched quite a few of his videos. They're interesting as much for what they leave out as what they propose.
I get where he's coming from, and have a lot of sympathy for the ideas, but this is one of those policy areas where the "common sense" fix hides a lot of complexity and challenges.