Also material betterment doesn't scale, we can't focus on material betterment for all because until we figure out fusion and get our own Dyson Sphere going, we have finite resources.
Is this actually established? It's my understanding that the work-leisure dichotomy didn't really exist in medieval Europe. Also, considering how much of the fruit of your labour ended up supporting local and distant aristocracy, I can't imagine mental health being particularly high for a lot of people.
* For source, I've seen Yuval Noah Harari and Peter Gray writing about it.
As Oscar Wilde put it:
Now and then, in the course of the century, a great man of science, like Darwin; a great poet, like Keats; a fine critical spirit, like M. Renan; a supreme artist, like Flaubert, has been able to isolate himself, to keep himself out of reach of the clamorous claims of others, to stand ‘under the shelter of the wall,’ as Plato puts it, and so to realise the perfection of what was in him, to his own incomparable gain, and to the incomparable and lasting gain of the whole world. These, however, are exceptions. The majority of people spoil their lives by an unhealthy and exaggerated altruism – are forced, indeed, so to spoil them. They find themselves surrounded by hideous poverty, by hideous ugliness, by hideous starvation.