It is your choice of course, I never said it was not. Why wouldn't I be sad for my friends being "sold a lie", that was presented as a sensible "choice"? It is like selling the lie that life in a touring tent is as valid as life in a house. In the winter most animals build shelters. As a rule most animals reproduce. It isn't social conditioning that makes us have children it is biology. We choose not to have them rather than the other way around. That is the social conditioning. Like thinking tents are "fun". Tents and being childfree are the "fairy tale" existence.
No, the tent was an example of how we choose to live.... after a bit choice is pretty irrelevant to need. Validity is about proof, perhaps the wrong word to use. I cannot prove that tents are an invalid form of habitation I can however see evidence that tents are usually morph into more stable "dwellings" for biological reasons of what humans need for shelter, safety, food supply.I love tents, they speak to me on many many levels, but I'm sure that over time my tent would become as socially conditioned as the rest of me.
I'm still trying to unpick the 'logic' of your metaphor, which reveals a lot more about your weirdly essentialist mindset than anything about choosing to have children or not.
For a start, who exactly is 'selling your friends the lie' that being childfree is a valid way to live? People who 'sell people a lie' do so because there is a profit to be made. Given that having a child is a great boost to business you need a nursery! A sidecar cot! A breastpump! A car seat! A new car! Toys! School uniforms! A trampoline! Childcare! etc etc what is the benefit to these mysterious forces 'selling the lie' if people choose not to have children and not buy mad amounts of child-related consumer goods? Who benefits from people remaining childfree?
Who is telling anyone that not having children is a 'fairytale' existence? If anything, the negative stereotypes of the childfree are still far more prevalent. I was happily childfree till just before turning 40 and I must have heard all the lonely old age/chilly, hard-faced careerist stereotypes a thousand times.
And your metaphor is really weird. The childfree by choice are like primitive people who erroneously believe that living in tents is as good as living in a house? Tents are flimsy and mobile, while houses are solid and stable? Are you suggesting that lives that don't involve raising children are flimsy and untethered, while lives centred around children are more 'evolved' and strong? 
Honestly, as I said, I was completely happily childfree until I had my son aged 39, and life is not dramatically different. I didn't have him because of any biological urge, or social conditioning, I had him because I thought it would be interesting, and it is. But my life before was equally good. I haven't turned from a tent into a house.