This seems very expensive for what a PC can do :(. A PC can be fully customizable with price ranges that are lower than the steam machine. The "hardcore console gamers" live on PS, and Xbox, and for "casual gamers", a Nintendo Switch would provide much better bang for you buck.
Find me a PC in this form factor that is as well tested and supported as the steam boxes are, with the specs they are claiming to have, at this price. Its a little above the curve but a little is not a lot, and you get a fully supported Linux box at that price.
.....and if you think this is expensive just wait until the PS6 and new Xbox are released.
You can install a SteamOS-style console experience on any old PC, including handhelds or mini-pcs with integrated graphics. Bazzite is a great choice for that, even my RX560 handles it without issue.
> a Nintendo Switch would provide much better bang for you buck.
A secondhand Steam Deck would also be better value, but this isn't a value-focused product. The Steam Machine is Valve's second stab at the premium couch-based PC gamer market, this time with Proton and a bigger focus on controller usability for ordinary PC games.