What? A personal assistant is someone that you know, that you vet, that you can gauge the skills and reliability of, and that you can hold genuinely accountable. And you are comparing hiring this person on a full time basis to an ad hoc and in many cases inferior "assistant" who is only available for a fraction of that time with no guarantee or indication of quality ahead of time.

And not just that, but only extremely rich people have truly personal assistants, and if they can afford them then they probably don't need this apparently mass-marketed service. Most "personal assistants" are hired by a company that the said "rich person" is involved with, making it a company expense. And why would a company with the resources to hire a personal assistant (and likely other flexible personnel) go to some $100/hr service when they have their own employees to service their general needs and who can be responsible for tracking down and hiring the specialists who actually do those tasks.

I mean, seriously. You could hire a full-time minion to go out and find and pay specialist deliverers, caterers, etc. for a similar or smaller cost than it takes to hire someone unknown and unreliable to do it ad hoc for a quarter of that time, given that 40hr/month estimate.