> It's hard to dig really big holes in the ground all day at random, but it's not valuable

Don't mistake "it takes a lot of effort" with "it is hard"

Digging holes isn't hard, it just takes a lot of effort

Speak for yourself, big-holes-in-ground are very valuable to me.

> but that’s part of why it is so valuable

“part of” leaves a lot of room for each of us to insert our own definition of “valuable” here.

Marx begs to differ. By labor theory of value Sisyphus should be the wealthiest man on Earth; unless you smuggle all the complexity and paradoxes of this theory into some ill-defined notion of "socially useful labour" (how does one measure or quantify utility?) of course...

Marx's labor theory of value very much still assumes a product of that labor to embody its value.