There is no presumption of scarcity, because scarcity is a real phenomenon.
There is a vast qualitative difference between the output of ten thousand amateurs and one highly trained and exceptionally talented artist (working in whatever medium.)
This an immensely unfashionable idea. But the real problem with DRM isn't that it does or does not enable copying, but that it presupposes that artistic output is a commodity that can be copied.
In fact artistic output - considered as the cultural influence of an entire career, and not as a series of copyable files or performances - is not fungible.
Not all content creators are equal. If you want quality as opposed to quantity, you need to set up a feedback function that makes some effort to reward and support quality, based on a more sophisticated metric than a lowest-common-denominator unit sales count in a mass market.
This is even more true of science. Ten thousand PhDs do not add up to one Newton or Einstein.
And politics. Ten thousand mediocre politicians do not add up to one Nelson Mandela or Gandhi.
By the time everyone is having the DRM or no-DRM argument they've already missed the point - which is that commodifying cultural output as "content" for industrial distribution mechanisms (including live tours) is to misunderstand how culture propagates and evolves.
And if you can't invent a system that finds and rewards talent - without reducing every transaction to the vapid foolishness of markets - then your culture, science, politics, art, and general joy in invention will stagnate and eventually disappear.
DRM is barely a footnote here. It's nowhere close to being the main problem.