> $600k/year operational against sub-$100k capital cost pays DBAs, backups, etc with money to spare.

One of these is not like the others (DBAs are not capex.)

Have you ever considered that if a company can get the same result for the same price ($100K opex for RDS vs same for human DBA), it actually makes much more sense to go the route that takes the human out of the loop?

The human shows up hungover, goes crazy, gropes Stacy from HR, etc.

RDS just hums along without all the liabilities.