AIBU to refuse BIL’s 40th holiday we can’t afford?

Exactly.

If the mother makes any more comments, he could ask:
Do you expect me to take out a loan or get into debt to join you all on this holiday? I will happily celebrate with a pint in the pub or tea and cake at our house but I am shocked you expect me to spend a thousand pounds I don't have to prove I am happy to celebrate a family birthday. Of course I am, but I am not happy to get in debt for it and not at all happy that you would expect me to.

YANBU! Why do people do this and put pressure on everyone! Stand your ground.. I know I would.

This. Two grown adults, who is going to force you?

MIL has said brothers should celebrate these things together ?
Well maybe MIL should be paying then!! It's not like it's a meal out or drinks in the local pub. Money aside, I wouldn't be using my annual leave on someone else's precious holiday of choice.

We have this problem in DP's family. They keep announcing holidays/expensive meals which they've obviously decided on between them, and then tell us. They have a lot of money as they inherited a really large amount each from their dad's dad, and DP is the eldest with another dad so got nothing. They go to the football together which we have no interest in, which is when I think the conversations must happen. So we can never afford to go, and therefore miss out on a lot of family things. Whenever we try to plan something cheaper, people are always busy. YANBU not going, and I am sorry that you're in this situation.

Even if your DH could scrape together enough for the actual holiday, he will still have to apply for and pay for an ESTA.
Also, as pp's have said, Las Vegas is horrendously expensive once there plus huge tips are expected constantly let alone if he got roped in with gambling which is so, so easy to do.
We have been twice and have to say it was great in the mid 80's but nowadays it is an overpriced sleaze pit and nothing at all resembling our first visit. Wild horses wouldn't get me back.

Why doesn't he tell his mum he will go if she's going to pay for everything, otherwise she has no say in his decision.

I think you should cancel your own holiday and/or other things you want or need to do and instead go on the very important 40th bash.

If you don't have enough cash still then take out a loan , and if the banks won't give it to you look for a shark.

Seriously, just say no. Firmly.

"We can't afford it" Rinse ands repeat.

OP, is this some sort of midlife siblings/family stag do or are you and your child(ren) supposed to go too?
Las Vegas isn't really a family destination and for a lads do, a week would be a long time.
I'd wonder what the participants would be expecting to do. Gambling for a week could cost a fortune and if it's supposed to be a family trip there are better places to have fun as families with the possibility of some gambling on the side.
Does BIL have a wife and children?
A bit more context would help.

yeah are you sure this isn’t DH passing on the pressure so you agree to sacrifice family holiday for him to go on naff LV shindig?

Or they can afford one ticket but two is a bit much 😉

I had a friend who replaced their roof to stop herDH going to his brothers wedding in Thailand once.

it was only when the family said they’d pay for him but not her that she found the money

Has your dh considered how much spends he will need /be expected to lose at the casino?
Anyone can declare they want a week's birthday celebration.. Only a knob would expect guests to pay.

Well YKWIM! Anything would beat a week in that cesspit of craps and hookers and exorbitant prices in LV 😊

I'd expect BIL to suggest a helicopter ride over the Grand Canyon to top it all off aswell. Yee Haw.

I've had the same question.
My guess is, DH wants to go and thinks they can afford it. OP thinks they can't. Family applying pressure on her as the once in charge of family budget.

This is very annoying of them! You can’t afford what you can’t afford so you’ll just have to say that on repeat. With these big things, you either have to to do them locally where people can come or you have to pay for people. You can’t expect someone to magic money from nowhere.

“Nothing beats a get together in the pub or house with a mahoosive birthday cake , lots of grog, plenty of food, and a bit of fun. People can come and go as they please.”

to be fair, plenty beats that 🤣

Why are you involved though OP? Surely go it’s for DH to refuse then for the family to offer to pay for DH if they want? It doesn’t really have much to do with you. If it was your brother you’d be sorting it

What the F is wrong with some mid life crisis sufferers approaching the big 40?

Nothing beats a get together in the pub or house with a mahoosive birthday cake , lots of grog, plenty of food, and a bit of fun. People can come and go as they please.

BIL's bash is a bit unrealistic in the current COL and world events climate. It's like a destination wedding. If I wouldn't go for my own holiday I'm not going just to be a hanger on.

Decline. Gracefully but truthfully and say no more about it.

Urgh! I wouldn't go to LV whether I could afford it or not. So naff! That's a very odd choice as it's a real marmite place.

Very odd to insist family go on a 40th let alone to Vegas. Don't make a big deal of it, just bat it off if it gets mentioned again and say you're sad/sorry but nothing you can do and change the subject.

I’m not sure what else there is to say or discuss. You can’t afford it. there’s no more discussion after that really.

I consider myself a fairly well travelled person and Las Vegas is the one of the most expensive places I’ve been. If you/he/together can’t afford it now, it will only be worse when you get there.

As lovely as it all to want to celebrate with our family and do all these lovely things, money is a factor.

Mil is being a bit ridiculous really. I’m a mum to all adult boys and I’d love them all to be together constantly. To celebrate everything together, to be together. But the reality is very different on so many levels, they all have varying levels of wages, kids, responsibilities etc

I suggest MIL should pay for it if she has a strong opinion. Even then it is your DH's annual leave and it's unlikely MIL would pay expenses while there.

Las Vegas! Has he factored in the cost of flights now after the Iran war? Long haul flights we booked 6 months ago for £800 are now £2k