We have a bunch of work that requires large, process heavy, calculations, so yes, vendor lock-in is a concern for us as it can mean either huge cost increases,

We have a bunch of work that requires large, process heavy, calculations, so yes, vendor lock-in is a concern for us as it can mean either huge cost increases, if the vendor changes pricing for the required instances upwards, or huge savings if a competitor can do the same computations for less. We solve this problem by making sure we can trash servers and spin them up elsewhere if needs be (mostly via terraform etc). I don't think this should apply to anyone running some hosts for web applications though.