Perhaps, except £5000 a month is way over average earnings as I'm sure you know. That'd be closer to £2000 a month before tax etc, so your 4 vaults becomes more like 10% of total income and a lot more of disposable income.
As for Zora's argument about cars etc, it's well rehearsed and redundant. Classic cars tend to retain their value, as do fine wines, whisk(e)y etc. you can't say that for a pixel prize.
One of my occasional weaknesses is for photobooks. If you choose wisely a book can rise by 200-300% in value (sometimes more) inside a year or two. Now tell me who's spending their money more sensibly?