And at that scale (1k) it ain't even that hard, a single room could be enough to hazardly drop them on shelves with a big fan to draw out the heat

There are many people who do not have ready access to a million dollars to purchase said Mac minis, much less the operating capital to rack & operate them.

Very smart play to build a platform, get scale, and prove out the software. Then either add a small network fee (this could be on money movement on/off platform), add a higher tier of service for money, and/or just use the proof points to go get access to capital and become an operator in your own pool.

If those numbers are true, they could tart with one Mac and can double every few months. But, I guess there are also many people who do not have ready access to whatever a Mac mini costs either...

You can run the simulation out, but if the idea works, you can get to scaled revenue much faster than organic growth keeping 100% of the margin.

This is essentially the same reason even the best money managers take outside money to start, even if they eventually kick out the investors.