It depends on how you are going to teach your kid on earning with bitcoin. For me, it isn't bad to teach them at early age on how to earn some bitcoins, since there are a lot of faucet sites, they can simply use it for claiming. And also it's not bad if you are teaching them on what's currently on trend with technology, just teach them how to use it properly.
do things that they want. Kids means minors and I believe bitcoin will only be good for matured people like those who are in the legal age already.
Yes, we know about it but we are in the modern days where everything should learn how to earn. If you will google out those kids that became CEO at very young age, they are grown up properly by their parents and thought them what life is, if you don't know how to earn then you'll be end up hungry and can't buy the things that you want. We are already in the new generation, where there's no age exception in making money.