Did you buy him in a pet store? Often shops will deal with hamsters very roughly so they’re scared of humans. All you can really do is always treat him with love and care, maybe coax him out with treats, and hope he’ll get friendlier. Some hamsters are just super shy though, so there’s a chance he won’t warm to you. It wouldn’t be your fault. By the way, did he squeak or bite when you grabbed him? Because sometimes hamsters just aren’t used to being touched but can get used to it as long as you’re gentle (and don’t chase them).