Now I think it's a myth that all childfree people have 'much more money' than people with children, and 'much more freedom' and 'much better holidays.' And that they can go off (for example) at the drop of a hat for a week in Paris 'because no children.'
Childfree people generally tend to work/have a job, and would only have so much holiday leave in the space of a year, and the cost of living is high for everyone, so many of them (especially the single childfree) wouldn't have any more surplus income than many people with children.
The people with children/parents may not always be high earners, and some of them don't go out to work (and are stay at home parents,) but many of the parents with lower incomes will have top ups of universal credit and get housing benefit. So not all parents are automatically going to be worse of than all childfree people.
Also the parents who don't work will have more freedom to just drop everything and go off on holiday. I know 4 or 5 families right now (with non working parents,) who have been on several long weekends away this year so far (and also a week or two in Spain, France, and Italy.) In term time too. They have just kept the children off. So they are actually less restricted in some ways than the childfree.
I think the only thing childfree people have 'over' parents is that they get to have a lie-in at the weekend. Yes, some will be better off financially than parents, but not all.
Then again, going back to your second point earlier, there is no guarantee of having support and someone to look after you when you are elderly and infirm, just because you have had children. I know several people over 75 who struggle with everyday life, and their middle aged children barely visit them, let alone help. They have to pay for home help/cleaners/carers...
I also know a few people (around 60 to 80 years old) who have children aged around early 30s to early 50s, who just use them as free babysitters/childminders for their grandchildren, (whilst the parents go out to work, and whilst they socialise/go to hobby groups.) They are permanently exhausted looking after these children, but feel like they can't say no because they're worried that they won't get to see the grandchildren.
So there is no 'one size fits all' IYSWIM.