Comment by londons_explore

Hybrid!

If you are at all cost sensitive, you should have some of your own infrastructure, some rented, and some cloud.

You should design your stuff to be relatively easily moved and scaled between these. Build with docker and kubernetes and that's pretty easy to do.

As your company grows, the infrastructure team can schedule which jobs run where, and get more computation done for less money than just running everything in AWS, and without the scaling headaches of on-site stuff.