You can over-provision your own baremetal resources 20x and it will be still cheaper than cloud. The capex talking point is just that, a talking point.
Your spend in the first year on AWS is going to be very close to zero for something like a SaaS shop.
Nor can you possibly scale in-house baremetal fast enough if you hit the fabled hockey stick growth. By the time you sign a colocation contract and order hardware, your day in the sun may be over.
