You ask how you can make him see that other fathers don't have this much to spend ........ well, show him this thread for a start !
Everyone - mother or father would like lots of disposable income to spend all on themselves as they wish. But when you've made the decision to have a child, you have to start being less selfish and putting the needs of the family 1st.
Then, and only then, do you get round to looking at truly disposable income. Many, many families have NO disposable income at all - they work to live, month after month, year after year and are "forced" to find pleasure and entertainment in things which don't cost a lot of money. It's not always easy. As others have said, there are also loads of households where income is less than (essential) outgoings and where each new emergency means the build up of more debt.
FFS - he needs his spoilt, bratty head banged against a very hard wall ! He doesn't know he's born.
Of course, there are a minority of fortunate families, who, after shelling out for all necessities have the luxury of a decent bit of "spare" cash - but in all but the most neanderthal of set-ups, this would be shared equally, irrespective of who went out and "earnt" it. So what if x earns £xx and y earns £xxx ??? You can bet that x (usually mum) is contributing to the household in other equally valuable ways.
Strikes me this "child" of a man is throwing a petulant tantrum because he sees "his" spends being threatened should you alter jobs. Oh dear - he will have to "sub" you if you do that - cue all his pathetic toys (role playing games FFS, talk about getting your priorities right) being thrown out of the pram.
I agree that if he can't/won't talk sensibly about this, then some counselling may be required. I don't think you've actually said how much you have to fritter each month ? ...... how come his poicket money is deemed so important compared to your mental well being ? Even if you loved your job, his whingeing about "only" £450 a month to spend is truly, astonishingly pathetic. He obviously believes he has some sort of "entitlement", no matter what else is going on around him - hey, where would you be if you suddenly adopted the same attitude ?