You love singing and karaoke is a great outlet for you but getting your friends to join in can often be a challenge so I will offer some tips that can help you motivate them to join you singing karaoke songs.
Everybody has their own reasons why they do not want to sing. Sometimes people are shy and sometimes they do not think they can sing well enough. So what you can do is let them know that having fun together and enjoying the moment is more important than being the next super singer.
People can often get embarrassed easily when they are the focus of attention. You can help reduce this by being the first one to start singing. You should always offer other people a chance to sing first but if they say know then grab the mic and sing yourself and enjoy yourself. Offer the mic to other people during the song and see who else is interested in singing with you. Reserve very popular songs and encourage everybody to sing with you and make getting other people to hold the mic a gradual process while they get comfortable and decide to join you in the fun.
Sometimes people will react better if you turn the volume down. I love my karaoke loud and you probably do too but getting other people confident and excited to sing with you is also important and needs to come first.
Often it takes one or two other people to get involved before other more reluctant people will join too and it is not always easy to get people to join you.
Always remember that not everybody will want to join you and some people will be offended and annoyed if you keep asking them to sing more than once so be very understanding and accept that karaoke is not for everybody even though neither you or I can understand why.
With a bit of friendly persistence, you should be able to get a few people in a crowd to sing with you and get a karaoke party going even if it was not intended to be a karaoke party.