Not much to explain, you're absolutely right. Hetzner would have been a much wiser choice here, but advocating any cloud provider at this scale probably has its perks too or he wouldn't be burning his money. Then again, perks only go so long and at some point do come to an end, so this is why he may be writing about costs right now.
Love how they are totally not ashamed to kick off the video with their collection of 14,000 mini-tower desktop PCs. Not rackmounted. Mini-towers.
Also totally ultra-curious about the PS/2 kvm. All those machines are from an era when USB keyboards had been around a long time already. Wondering if this is a security measure...
Take a look at their datacenter in Germany: https://www.youtube.com/watch?v=5eo8nz_niiM