"Mars will never be settled any more than Antarctica is settled."
This is a broken analogy in two ways.
One is that there's a huge qualitative difference between going elsewhere on Earth and settling another planet, and I don't think you can hand-wave that away. You might have no interest in settling another planet, which is fine. There are seven billion plus people on Earth, and all we need is about 10,000 over, say, a century or two who do have that interest. I think you'd have so many applicants for a serious mission you'd have to be very picky.
Secondly, it's illegal to settle Antarctica. It's all "claimed" and tied up in various treaties and conservation laws. What would happen if you opened Antarctica to settlement and allowed squatters' rights or land claim rights? I think a whole bunch of people who are interested in trying new political ideas, etc., would jump at it. It'd be significantly easier and cheaper than seasteading. There'd also be natural resources to be found, so you'd probably have a gold rush.