I read many comments on how PeerTube isn’t sustainable as a YouTube alternative and, while it’s certainly true right now, are we sure it will be the same in the near future?
The platform is growing and the new mobile app is making great progress; I can certainly see some people investing in a major instance some day, accelerating the platform adoption.
Disk space is relatively cheap, until you also count redundancy, backups, storage hardware, utilities, and bandwidth.
Redundancy and backup is automatically provided thanks to federation, other instances can decide to host a copy of your vid (see archive.com for example).
Bandwidth is provided by torrent.
Storage HW can be anything.
Ads are supported so you can monetize