Libertarian ethics allow a minimum amount of human cooperation including free trade, while avoiding force. that's very good. that line is approximately what the law should be.
it's also good for some people to cooperate more closely (ie, be friends). friends cannot automatically justify their actions by saying libertarian ethics finds those actions permissible. what works well for friends is a restricted subset of what is allowed for business partners. just because something is legal does and peaceful does not make it a good way to treat your friend. it could still be mean, callous, unhelpful, etc
one of the hallmarks of friends is that they sometimes help each other with problems. not because they have to. but because doing so benefits them -- both of them. helping someone is a perfectly interesting learning experience in its own right, but it also means having a better friend in the future which is nice. and later being helped yourself is good too.
if your business partner is annoyed by your hat, who cares (unless he will ruin the business deal over it. in which case you almost certainly don't try to reason with him about hats, or help him form better preferences. you either give up the hat or the business deal.) if an acquaintance is annoyed, you can say "who cares?", or not, your call. but if a good friend is annoyed, then while it's perfectly legal and libertarian not to care, that does not facilitate cooperation or coordination with him. it creates distance if you never resolve the hat thing and can only meet on days you aren't wearing a hat. better, generally, is to ask why he doesn't like the hat and seek a mutually agreeable solution.
even if it's entirely his fault -- an irrationality about hats -- still it is better to be helpful about it if you want to continue cooperation elsewhere. why let this little hat problem get in the way of the mathematics paper you are writing together? or your ski trip? or anything else of importance.
Most kids are dirt poor. Not because their parents are dirt poor, but because their parents don't give them much money. This is partially and inadequately made up for with gifts, and with the ability of children to ask for parents to buy things. Children should not need parental approval to buy things -- what that really means is that if they disagree then parent gets his way by force (if they agreed it doesn't matter who is in control). Having to go through your parents also compromises your privacy. And also parents generally think kids don't need much, and prefer to keep the money (how self-serving!)
Parents prioritize a lot of things above wealth for their children. Such as lotto tickets, beer, cigarettes, kitchen remodeling, new cars, vacations, and generally whatever else they want.
For now I will make one simple suggestion: is donating to charity really more important than giving your poor kids more money?