There’s a lot of black and white thinking on this thread. Not all holidays are pointless, only staying in a resort and gaining no cultural experience (which anyway has its own benefit). Not all cultural experiences are going to create super well rounded individuals. Not all intelligent and well rounded people have been abroad. Going abroad for arseholes won’t make them wonderful and caring. Two weeks in Spain will not make your child bilingual, nobody’s saying that. Surely it’s a two-pronged bit of reasoning; can you afford it, and is it something you want to do?
Travel is a massive luxury, yes. Doesn’t mean there’s no benefit to anyone in doing it. If you can’t afford it, but want to, that’s not great. If you have no interest in travel, that’s fine too! I don’t get the hate for travel for people who can and want to do it. People who travel a fair bit, speaking for myself, are not then going without trips to museums or other extra curricular experiences - it’s not necessarily one or another.
I have been on lots of trips with my kids. We plan and get involved in local culture, learn a few words, look up the stems of the language and way people communicate. What’s considered rude/polite and why? How did their cuisine develop (me and my kids eat more than chips)? We relax, switch off from work and school and immerse ourselves in another world - whilst yes also lolling about round the pool and eating ice cream. I don’t think my kids would be ruined by not doing any of this, but we have a brilliant time, and we do engage with the customs of wherever we are. Why does it have to be a waste of time just because it’s not a priority for some people? Many people can afford it, but choose not to do it. Some people can’t afford to do it, but equally don’t want to go abroad anyway.
My kids are ND and get a lot out of being away. Some will hugely struggle and cope better at home. It’s like arguing over what someone’s favourite dinner is. Everyone’s got individual preferences and budgets.
In answer to the original question, travel IS a luxury, of course. Does it make people more well rounded? No. Being well rounded takes a lot more than going on holiday. My kids travel a lot and are well rounded, but we have a house full of books, watch a lot of documentaries, they do a lot of free after school stuff and we go to free museums and galleries. I’ve also been open with them about life and people and the world around them. I’ve removed toxic people and situations from their lives, engage in their education. Travel is just a (for me) fun add on.