American is actually pretty flexible about this. You can use your AAdvantage miles to book award tickets for anyone, friends or family, and you don’t have to be on the flight yourself. It’s completely allowed.
The only real rule is that you can’t sell miles or tickets as a business. Having friends reimburse you privately for what a cash ticket would’ve cost is common and generally fine, just keep it low key and don’t advertise it.
A few things to watch out for:
The passenger name has to match their ID exactly
Once booked, changes or cancellations are controlled by you, not them
If something goes wrong day of travel, you’ll probably be the one dealing with AA
For value, you’ll usually get the best bang for your miles on:
Domestic economy when cash prices are high
Last minute flights
Short haul routes where AA’s fixed award pricing shines
54k miles can go a lot further booking for someone else than burning them on a mediocre trip for yourself later. Just make sure everyone understands you’re the “ticket owner” if changes are needed.