I mean, $7,000 a month isn’t nothing. But it’s not a lot. Certainly not enough to justify a seven month engineering effort plus infinite ongoing maintenance.
7 months is presumably more like “the time it has been stable for” or so, although I am not sure the dates line up for that 100%.
Also cost reduction was apparently not the main impetus, GDPR compliance was.
You can’t avoid this cost. Some people refer to it as technical debt, but I think more accurately it could be called “infrastructure debt”. Platform providers maintain the infrastructure debt for you - this is what you pay them for. And they do it with tremendous economies of scale. Unless your scale is truly enormous - like Meta, for instance - it isn’t worth build your own infrastructure.