I am avoiding quoting specific threads as I know it is against the rules. However, I have seen a number of threads where the OP has been disappointed that certain friends have not shown any interest in their significant life events. Having a baby, buying first house by way of an example. The overwhelming concensus of replies to these type of posts seem to be that you cannot expect anyone apart from immediate family to care about your significant life events. People apparently have their own stuff going on and are crazily busy. To expect any level of interest is entitled, needy and demanding behaviour.
This genuinely surprises me. I would definitely be interested in things going on in my friend's lives as I care about them and want to see them happy. If I didn't, I would only class them as acquaintances. Even if they have stuff going on that I have no experience of, I would still express interest because I know these things are important in their lives.
I can't help wondering if a lot of people on MN would not be very rewarding as friends as they would only engage with topics of conversation are relevant to them?