As someone with a 17 yr old, 5 dn's and decades of experience looking after other people's children - I find these threads are excellent for spotting the parents of children who will not be INVITED to parties in the near future.
Abuse is wrong but discipline is a necessary part of parenting and that seems to be getting forgotten imo in recent years. It does children NO favours not to discipline them. Not to teach them boundaries and what is acceptable behaviour.
Op yanbu to follow through.
1 a party is the last thing he needs if he's tired and on edge
2 kids - yep even 4 year olds - are not stupid. You back out of a threat they will smell blood 😂 it weakens your position in the future.
3 he absolutely IS old enough to understand this is a consequence of his poor behaviour
4 it would be unfair on the birthday child and their family to have to tolerate a poorly behaved child possibly upsetting others.
Graduated discipline (which the op has ALREADY DONE) is completely sensible, but at some point as a parent you have to say enough is enough or else you're going to be raising a child who doesn't understand boundaries and that is going to impact on friendships and achievements.
I've seen long term the effects of soft parenting, it doesn't serve the children well.
"I'm seeing the results of the kids who "are just 4" "are just little" "are behaving that way because overtired" and who didn't have parents who followed through." Exactly!
I've seen it particularly with a girl my dd was friends with from primary but her mum NEVER followed through. As a result she's very entitled and has lost all her close friends now, the "friends" she has now are only friends with her because of what she can provide them (single mum and nrp dad both ridiculous on material stuff to assuage their "guilt" on her not having a traditional family)
My sisters children the same is happening. We're Nc but small locale so stuff gets back to me. Her eldest (a very bright, confident child) is repeatedly getting in trouble at school, middle child is struggling to make friends, youngest is still tantrum central aged 5.
I've seen the difference with children I've minded/nannied too.