So what percentage of your total monetary and financial investments are in Bitcoin?
i am not gonna answer this sorry, because it is so personal thing

What do you think is a smart balance to have?
but the number doesn't matter in my opinion it is different for each person, becase every person is different when it comes to taking risks and investments. most people look for a safe investment rather than high risk high reward.
You have to take a big risk for a big reward.