Re: I will invest in bitcoin for my child's cost when they grow up.
I see lots of people who have long term success investing in bitcoin. for example, like people who bought bitcoin in 2009 and sold it in 2021 when the bitcoin price was high.
I don't think people who brought bitcoin during 2009 and hold it till 2021. There were a biggest pump during 2017-2018, So I don't think they could control theirself and hold the bicoin without selling 
except they forget that they had some fund in other wallet. Or the its too much rare who keep holding till 2021. Btw its a good idea you want to invest in bitcoin. But make sure that you have already enough for your living cost for atleast a few years. And only invest the amount you afford to lose. Anytime anything bad can happen in crypto so keep prepared Your self to control yourself that time.