I don't think Medium makes money from free reads, unless someone joins Medium. So I don't see how they're making money or exploiting us. It's just a blogging platform, like Blogger, except we get paid. There's no advertising generating an income on free reads. Whether there should be is another matter entirely! Some people feel there should be advertising so that we can all be paid for those free reads.
But then just recently, they put the paywall up permanently, so people can't have 3 free reads anymore anyway. But they do get a longer preview, which is quite substantial. Some of your clappers might have read the 2 minute preview and liked it.
You know you can turn on the tips feature, presumably? It's a bit like subscribing to Substack, in that it's a voluntary donation.