I sort of keep mine a secret, I tell some people and some people I don't! It's completely up to you who you want to share it with but if someone has a religious, moral or sceptical issues with tarot and divination, there could be consequences.
I don't really care to be honest if people find out, it's a hobby and interest of mine and I love it. Most people have at least one odd / unconventional hobby that they only share to their close friends
But I don't tell everyone and keep it a little quiet in some areas of my life just because I don't want to be mocked really. It's just easier currently.
If you are learning, feeling a little lacking in confident about yourself or really need to live with your family / live in a very conservative area, I would be careful. But it's up to you who you want to tell. Nothing wrong with it but it's a little sad when people don't know an interest of yours that makes you, you!