An individual who appropriates an excessive share of market income will be regarded as having paid more income tax than persons less able to claim large shares, but may have made a smaller net contribution. The second form of social contribution is non-market production. This includes a whole range of unpaid activities that take place at global, national, local and household levels. A welfare system that facilitates a balance of the three different forms of contribution is more valuable to human society than a system that forces everyone to contribute through just one of the three forms. Indeed, mass labour market participation may contribute even less, net, than mass idleness.
Variety is the spice of life.
Variety of contribution is the means of safeguarding society. People like to focus on it, but it is really irrelevant. Any system will have a small percentage of abuse - any system you might name. The other third have coming the entire 8 years, and likely many years before that. Most are able-bodied.