Unless you are Banksy, the Batman of the art world, you should let people know who you are. Encourage them to know a little bit about you so that they feel more comfortable investing in your art and talking about your work to others. You want to put a face to your artwork like a business owner who stands behind their product and an artist bio is just the place to do that. When your fans and patrons have key points of info about you they can repeat it while they are endorsing you and your work and you give them the confidence and permission to do this with a public artist bio.
An artist bio is different from an artist statement as it's less about your art and more about you. Some artists combine their statement and their bio but I'd encourage separating the two. Whenever you are writing these art documents remember that it is a real point of agnecy for you as a spokesperson for yourself. I mean that you get to make choices that should reflect you and your personality. The bio you write can be casual, co-conspiratal, fatalistic, dramatic or irreverant. No one can tell you otherwise because it's your statement. I once read an artist statement that was the reason the artist wouldn't write an artist statement. Her work was all quite humorous so this actually worked really well : ) I tell you this to take the pressure off and remind you to have fun and take risks wherever you like. YOLO.
However you write the artists bio these are the questions you can consider answering with your bio:
Who you are?
Where you are? Where you are from?
Why you make art?
Or if that's too general , What drives you to make your current work?
What get's you into the studio?
What is your studio practice like?
What does it look like in your creative space?
How Long have you been doing this?
Do people buy your work? Is it in any collections?
Ever won any art prizes you want to brag about?
What makes you special?
Do other artists inspire you?
How are you involved in the art community?
Where can people find your art if they want to see more?
Where can people find your art if they want to purchase it?
Do people deal with you directly if they want to buy art?
If your don't know where to start - answer these questions and write it all down. Then pick out the answers that you think are the most interesting or that you think people would want to ask you. If these questions don't do it for you then interview yourself - write a set of questions that you would ask yourself to get the most interesting answers. Read other interviews for inspiration!
A short paragraph is fine for a bio. Rewrite it often and add and take-away from it when it serves you best. If you use the same bio for too long you may find it to be a bit stale so let it evolve with you as your work changes, your process changes and you change.