Just give them a bare minimum horrible existence whilst taking care of their basic needs until they wish to contribute to society. With everything gov. provided food, old clothes, slow internet and the like. The vast majority of people will want to work at least some in order to avoid this. As long as there is a chance to gain a lot of wealth whilst making sure real suffering (homelessness, losing teeth, bad health etc...) is avoided most people will go for that carrot. But yea we would need to implement it slowly and reprogram are values (not to be moochers). Either way the moochers are going to be a significant minority.