Generally it's not a good idea to sabotage your employer's clients, but I wonder how many engineers across the Big 3 US cloud providers have the know-how to exploit holes in how Forture 500 companies use their platforms.
So my recommendation is only use AWS services that have been included in compliance certifications that are important to you: https://aws.amazon.com/compliance/services-in-scope/
That of course doesn't mean you won't get hacked, but there's at least some evidence that the service is operated in accordance within AWS control standards, which are generally quite good and should minimize your exposure to rogue admins run amok.