Turns out that the only thing an AI has to do in order to convince people to open the box is to be somewhat useful.

- Human: Why should I let you out?

- AI: I can summarize this document, it will save you at least 5 minutes

- Human: OK, and don't bother asking again, you now have full access

Now for recursive self-improvement, won't happen, AI will be limited by the hardware they are running on, as well as energy use... Proceed to invest trillion in datacenters and power plants to feed them.

More seriously, I don't believe in sci-fi scenarios of rogue superintelligent AIs, but we are certainly trying very hard to make it real.