Brilliant post @RubyGoose99
Being unable or unwilling to spend £500 on one meal doesn't mean someone is bad at planning or budgeting.
Or that they are tight FGS!
Well, no, not at all. It just means that they can't afford an expensive celebration. They can still have a celebration, a get together. Buy tea & coffee & cake in a café, or just drinks out, or a picnic in the park, or invite people round for drinks and nibbles etc. A luxurious, expensive celebration like a full meal and drinks in a fancy restaurant is outside of their budget, that's all. So they pick something within their budget.
Or they ask friends and family to join them at a restaurant with the expectation that everyone pays for their own meal. Why do you find that so hard to understand @dontmalbeconme ?
Said friends and family won't expect their meal to be paid for because they don't move in the kind of circles you clearly do where you expect to be "hosted" every time you are invited out.
This kind of "etiquette" is reserved for the privileged who have plenty of disposable income.
Your idea that people can't celebrate a birthday with a meal out unless they offer to pay for their wider family is, quite frankly, ridiculous.
I agree @SandyHappy And written by someone who is so used to their own privileged life that they can't envisage that most people don't live like this.