Not necessarily secretive the way OP feels, but a bit careful perhaps. When you start telling them what you are doing, oddly enough that you will end up answering endless questions. Some are out of curiosity while most are out of sarcasm. So to avoid these unseeming situation, I prefer not telling anyone especially those who cannot relate to it. But if I sense that they are really interested and open-minded, I share my knowledge about crypto trading with them.