It's OK to be cautious. But the very first person I scam would post that it's a scam and there will be no others.
I don't say that you do scam or not but the scammers are intelligent these days. For example, if you were to scam, you wouldn't do it initially, try to gain trust, pretend to be very fair, and once you get enough API keys, then you can proceed with your bad intentions all at once and get maximum benefit.
Again, I am not accusing you of any scam as there is no evidence yet, but we are all trying to be cautious as we have experienced such things in the past.