As someone who has a mortgage and kids my theory is usually that if it works out at least £1 per hour played then it was money well spent otherwise its just too expensive.
For single player story games which I know I won't go back to I sell it on after I complete it and lose very little money if any at all.
For example I bought Spider man 2 used for £40 and sold it 3 weeks later for £40, basically played it for free, it's still £70 on the psn store...
Games like gran turismo, battlefield, cities skylines, cyberpunk etc I have hundreds of hours in so in those cases £60 would be well worth it.