It's something you just have to accept. I wouldn't exactly force someone to be interested in something. It's their loss if they're not interested. It does take time, patience and effort, especially with recall and awareness. People place different values on different things. We just happen to place value on lucid dreaming and the experiences it can offer. The best we can do is introduce it to people who we believe could appreciate something like this, and if they don't, then just let it go.

Trying to "force" someone to like it or practice it will probably be an almost guaranteed failure for them to go through with it. I didn't exactly get results for weeks and weeks when I first started, so if a person originally was against it, the time it takes for results may just confirm their initial suspicions that it isn't worth it (in their opinion).

Don't take their lack of interest personally. Just be happy that you're doing your best to grow in a new way. They'll hopefully find their own path of personal growth.