Ah that one is surprinsingly easy, you justify the cost by facing facts. Did your company lose money during the downtime, and if yes is that sum more than what it would cost to have this redundancy ?

No ? Then the costs are not justified, and while it would be better from a tech perspective it makes no business sense.

Yes ? Well then you spend X to save Y, with Y being greater than X, so it's an easy sell as long you don't start with "cloudflare is never down" (which is not true).