Yes, no doubt about it the fastest to multiply your bitcoin is through gambling or betting, Maybe in just seconds you can double your money or any sort of cryptocurrency, But the downside is you can also lose all of your bitcoin or money in seconds. It's very risky I don't recommend doing gambling. Unless you have extra funds and ready to lose.
Gambling and betting on many sites surely doubles your money if and only if you are luck enough. The risk on playing gambles will go higher and higher as one person being addicted. If you really want to play gamble, it is correct that you are ready to lose and you have an extra money. Gambling can double your money but also it can also lose your money in an instant.