Again this isn't how it works, your contributions are to pay for those currently receiving state pension, not your own pension in years to come.
Kind of like a state-sponsored Ponzi scheme, really.
If the UK is sensible they would look at the history of countries that have imposed this and copy the best features and naturally reduce state pension needs.
But you don't magically free up a lot of extra money by forcing people to pay it.
It's effectively saying "If more people were richer, the government wouldn't need to pay for them - so, folks, just to let you know, you need to get richer!"
This will most probably result in very low earners missing meals and maybe even rent payments in order to save money that they can rub together for the future that they may never have.
It could also be another new crime that many poor people will be forced into. Imagine the government prosecuting you for buying food with your money instead of stashing it away. Still, I suppose, at least living is a lot cheaper if you're in prison, eh?