By having a better life. I might adopt etc and generally live a less impactful life as i would have the cash. Everything Organic, The home super efficent etc. I could support my friends etc
What makes you think you'd actually have the cash?
If rich people no longer have that money and everyone else has it instead, things will just end up costing more. You'll still be as proportionately penniless in the end, and the money you spend on all those things you'd buy would just go back into the pockets of the formerly rich people, making them once again rich.
Redistribution of wealth has been tried several times, and it always ended up with the rich people regaining that wealth, mainly because the poor people still spent it.
how do these people use the money? Putting it in an offshore account with Bentleys and Mansions?
They generally loan/invest it somewhere, which is what funds things like maintenance of the public clean water supply infrastructure, pension schemes and all that stuff.
What was that fact i heard, Is it true that something like 25% of the UK currency is not accounted for aka hidden somewhere unused?
If you mean actual currency, as in bank notes and coins, then quite possibly... but that will likely be a combination of withdrawn denominations and under-the-matress savings, both of which will be spread across the whole population and likely more common among lower and middle classes who don't trust banks for whatever reason, rather than the rich elite who are more likely to
own the banks.