Milestones are there to be celebrated.
It is only natural to want some recognition when we achieve something big, no matter how many other people have been there before us. The likelihood is that we had to work hard and go through a lot to get there, and that deserves some attention. Having a party at the end of it all is the logical conclusion. It’s not like a lot of people want to have a huge celebration every time they do something; they just like to feel as if they are giving it the acknowledgement that it deserves.
Taking this into consideration, it is no wonder that family drama and fallouts often reach their height around milestone events and their celebration. It can really bring out the most upsetting parts of those relationships that were not in a good place to begin with. Some people only want to show up when things are going well, and not when their supposed loved ones are struggling. Others do not want to engage with their life at all, whether what they are experiencing is positive or negative. No matter the issue, it is upsetting to deal with as the person who just wants to enjoy their achievement.