It's disgusting to feel jealous because your parents are enjoying their retirement. Nobody is owed anything, parents already raised the kids and anything extra they get is a bonus not a must.
My parents didn't get any inheritance, I won't get any inheritance; opposite, I have to help and give occassional financial assistance.
I'm a millennial and have worked hard for everything I've got, made many sacrifices to buy my own house and get any luxuries I get. Of course, I'm blessed that my parents gave me a university degree and I'm healthy enough to work a full time job.
As other people have mentioned, to give kids money when you haven't died depends on life choices, relationship with kids and circumstances. You can't expect no or low contact, and get money all the time from the parents. Did they choose to study? Did they choose to work full time? Relationships are complex and if kids are close enough to the parents, the parents would help but it depends on all those things.
Example, my brother chose not to go to university, chose to stay in a low paid job with no benefits when I offered to get him another job which was also low paid but had very good benefits (health insurance, low % loan for housing, etc). Chose to marry a women who only got him on big debts and left him. He's struggling but I can't be helping, if I do it, it will be forever. Have given him loans in the past which are rarely paid back. In these circumstances, its harder to help. Same would be with the kids.