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.