This is nothing against the anon, but posts like this make me so sad. Like people really have no idea
1. how much it costs to store their gif sets and serve web traffic and push notification and w/e
2. how much Zuck and others have been making from brutally harvesting and exploiting your private information
3. that maintaining a social network like this is a full time job for MANY highly skilled people, and that running datacenters is expensive, and using cloud services is more expensive
4. Like seriously, how is your mind not blown every day that you can still view some gifs uploaded in 2007. That's 10 megabytes that's been viewed (downloaded) a million times. Perhaps some were viewed 100 million times. That's 1'000 terabytes (1PB) of traffic just for one popular gif. It had to be on several hard drives, safely, all that time. You've been lied to if you think that costs nothing.
And again, not saying this about anon and not judging anyone but like. Statistically, over 99.9% of you don't want to pay for Tumblr Premium. How many of you would suddenly want to pay for Open Source Tumblr. How would you talk to the New Staff. How would you react if you disagree on any UI changes they make. If people send death threats to staff over a free social network, how much more entitled do you think people will be if they actually have to pay for it. What if you see some CSAM or revenge porn or something. Who will review it. Who will delete it. Who will be in charge of banning those users. Who will read bug reports. Who will validate complaints about inappropriate DMs. There literally is enough work for hundreds of people every month even with a financial sinkhole as Tumblr is right now. How do you think it would get managed as a community project. Who will keep track of 200 volunteers. Who will replace them when they burn out. Who will make sure there aren't power hungry cliques abusing their power. Who will make sure it's not hijacked by political parties or corporations to push their propaganda and oppress or data mine a minority and sell the data to ICE. Who will make sure a creepy mod isn't just reading all your DMs. Who will carry the legal responsibility if Nintendo sues the site for copyright infringement. Who will do audits. Who will represent it in court. Who will respond to DMCA takedowns. Who will wake up at 3am to mitigate a DDoS. Who will take legal responsibility when the database gets hacked and email addresses get leaked. Who will make sure the database admin isn't actually working for NSA and that's why he can afford to volunteer for free.
Running an ethical, large-scale, rich-content (with images over a few kilobytes large) social network is just incredibly complex. And by complex I mean impossible.