Well the argument that you shouldn't let people decide because it would be utter chaos (look at this riff raff!), that argument is as old as the idea of democracy. You might be right in case of twitter, but you used the same arguments that is very much in the hearts of the fascists trying to grab power right now. And the policies of social media are very much a factor in this too.

And why can't a company be run democratically? Either by the workers that are creating the actual wealth, or by the users, or some mixture of it? Why can't they elect representatives / managers and decide what to do with profits and where to invest?

The capital of a social media is really it's users and it's users private data. Otherwise it's a relatively simple software. This is quite different from many other companies and strikes me particularily as something that shouldn't be owned by capital, because it is so sensitive. And because it's more like a public utility.

If social media was run democratically, the first thing they'd vote for is more privacy. Then for less ads. Or maybe to invest more in bots and customer service checking on bots. They'd ask to institude a system to limit offensive shitposters and trolls, or paid for political misinformation. I'm pretty sure the actual developers would want very similar things because they want to create and offer a good product and are not fussed about increasing shareholders profit.

Instead some rich fuck comes along, buys it and changes the name? "Oh you're using X today because I think that sounds cool!". That strikes me as rather offensive and almost disparaging, like saying to millions of users "oh you don't get a say, I own this. I know best".

They can leave but they loose the connections they made. They can switch to mastadon or similar but it's far from sure if that will be successful and another thing if this is actually an overall benefit to humanity.

Or said in a different way: How can human civilization progress in positive ways when the means of communications are owned by those who have entirely selfish motivations? It might be possible to show through some mathematical modelling that it's actually impossible to reach desired outcomes with the current setup.

Overall democracy hasn't been improved but very much minmaxed by special interests who tweaked the rules and created institutions to control everything. Worst of all the minds. Why shouldn't we improve our democracy? It's clearly not working. And why shouldn't we have a fifth estate, separate from the executive and legislative, to control the economy?

But you're not even allowed to suggest any of this because the current status quo that everything should be owned is so ingrained in peoples minds. There is the left and the right and anything not on that spectrum is clearly insane.