But I get no protection from these tech overlords, they can close me down at anytime or give my data away to third party or the government without my knowledge.
The analogy is that you get to use their platform to build your 'brand'.
Of course other important aspect is that even if you are free to move to a different platform - in contrast to serfs, who in general had to ask for permission to move - you can't move your followers. So in that sense every second of effort put into a twitter profile is improvement to the land that you can't take with you. And, as we know, while brands are important users are lazy and stick to platforms much more than to brands. (While, again of course, there's usually a very devoted core community around content creators, but that's not true at all of most brands, and especially not true of regular users who just want to have some Reddit or forum-discussion-like experience.)
Of course other important aspect is that even if you are free to move to a different platform - in contrast to serfs, who in general had to ask for permission to move - you can't move your followers. So in that sense every second of effort put into a twitter profile is improvement to the land that you can't take with you. And, as we know, while brands are important users are lazy and stick to platforms much more than to brands. (While, again of course, there's usually a very devoted core community around content creators, but that's not true at all of most brands, and especially not true of regular users who just want to have some Reddit or forum-discussion-like experience.)