The steam machine may be cheaper in the long run once you consider:
* Playing PlayStation games online costs $11/month.
* PlayStation games tend to be more expensive than steam games.
Where can you get a new gaming "beast of a machine" for $600? In the past you could build a reasonable gaming machine for $600 but parts are drastically more expensive today.
If you go to microcenter and look for gaming PCs, their cheapest option is $800 [1]. PC Part Picker's entry level build is $780 [2].
The only option I found with these constraints is this computer from Walmart with a GPU released in 2017 and a CPU released in 2013 [3] (This is not a recommendation for this listing. Please don't buy it).
[1] https://www.microcenter.com/product/705867/powerspec-g530-ga...
[2] https://pcpartpicker.com/guide/fQscCJ/entry-level-amd-gaming...
[3] https://www.walmart.com/ip/STGAubron-Gaming-PC-Computer-Desk...
...funny that so many people were complaining about the recent Steam Machine not being worth it compared to just getting a PS5; maybe now it's not that bad of a deal after all, huh?