Even if you get the tech stack solved to an easily deployable package: The problem is you still need to invest immense amounts of time on moderation. Some of that responsibility is enforced legally (e.g. CSAM, warez, US COPPA, EU GDPR, German NetzDG), some of it socially (e.g. kicking Nazis, conspiracy spreaders or other forms of hate speech out), some of it by the federation system (e.g. kicking spammers out) and some of it you need to do to keep your community healthy (e.g. kick general trolls and creeps out). If your instance allows adult material, gambling or games, you'll need to moderate your instance as well in some jurisdictions. And you'll need someone always available to support police, court and secret service requests.
Maintaining a service that hosts user-generated content is a thankless nightmare, and no matter what you do it is a huge liability. In the end, either you make your users pay for it in cash (subscription fees, patreon/gofundme/paypal donations), with their data (advertising) or you'll eventually burn out (such as the author of the blog entry).
Oh, and add on top of all of that the constant dealing with abuse: 4chan edgelords DDoS'ing your instance "for the lulz", random skiddies constantly running exploit scans against your server (which additionally means you have to have someone 24/7 to upgrade software in the case of a 0-day), people reporting your server / IP to blocklists to get you booted off the net... then you have to take care of hardware maintenance itself, making backups, testing backups. It's a full time job essentially, requiring an awful lot of time, money and connections (e.g. lawyers).
