I'm a very active user of Magic+, so I'll give my perspective. (and of course I've been working with them from the beginning at YC, so you're also free to discard my opinion as biased)
For me, Magic+ is basically the impossibly good personal assistant, kind of like Jarvis in Iron Man, or Emily in The Devil Wears Prada. Unlike a conventional assistant, it's available 24/7, always happy to take on more work, and capable of accomplishing just about anything.
Obviously the $100/hr price point puts it out of reach for most people, but my expectation (as an investor) is that as the tech improves, they will be able to bring down the price while maintaining or even improving the quality of the service (I call this the Tesla strategy).
For me however, $100/hr is totally worth it since it effectively increases my leverage and enables me to get more done in less time. I've used it to plan events for YC founders, answer questions that are hard to Google (they will find the right experts and ask them), and provide unique and memorable gifts to friends, family, and business partners. I'm used to paying a high price for quality professional services such as accountants or lawyers, so $100/hr for the best possible assistant feels completely reasonable and rational.