Both Microsoft and Google are working on building Quantum Computers. Google achieved Quantum Supremecy in 2019. Microsoft already has a website that previews Azure Quantum. Given that both companies have cloud offerings and the first Quantum Computers are going to be really expensive it makes sense to rent out compute on those computers to willing custumers of their cloud offerings.

When will it be possible to buy Quantum Computing via the Cloud?

This question will resolve as the day on which quantum computing services can be brought via the cloud (as normal compute in cloud computing can be brought in 2020). On the date of resolution, prices for quantum compute must be openly advertised and any user must be able to sign up without first having to be on a waiting list. If these conditions are not met by the end of 2050, the question will resolve ambiguously.