> managing your own bank of SSDs

If I have enough data to need multiple SSDs (more than 8TB) then the cloud cost is not going to be substantially less. B2 is going to be above $500 a year.

I can manage to plug a backup SSD into a phone charger a couple times a year, or leave it plugged into one when it's not in my computer being updated. Even if I rate that handful of minutes of labor per year at a gratuitous $100, I'm still saving money well before the 18 month mark.