What's preventing Bitcoins from being accepted as mainstream payment forms? I'm working on a new blockchain and would like to learn what drawbacks of Bitcoin urgently need to be improved

Some of the countries said that the crime rate is increasing because of cryptocurrency and i do not really think that this is possible because, there are a lot of people who are already committing crimes when bitcoins is not yet existing, they are just creating black propaganda to reduce the investors because their business is being affected.