Well TBF most proposed UBI systems just provides enough just to buy food, clothes and basic utilities there will always be a need to find some form of Paid employment imo
But yeah I agree if you are in full time work you shouldn't need the benefit system but we do due to stagnant wages and...
God Forbid you offer anything other than NMW with no benefits. No wonder why the locals aren't flocking to these jobs lol.
NMW Hauliers for example will ruin it for non-prisoner haulage drivers who were on £10-£20ph.
There will be another population boom and then the population will stabilise around 2100, the best way to combat overpopulation is to develop the third world, it'll increase population initially but will lead to the Birthrate being below replacement levels.