>>512856980
As a means-tested benniemong you have to declare everything, including cash. If they find out you've been hoarding it then you're totally fucked. If you make a big investment purchase they'll be on to you. For example, you have to give your details to gold dealers so they can pass it to HMRC. If you keep it in cash it's dissolving like an ice cube through inflation.
Non-means-tested benniechads don't have to worry about all this, they can siphon their bennies directly into an ISA, or buy gold or crypto, investing it in something returning 10% or more a year completely tax-free if it's in an ISA, all with free money.