(he's retired)
Some people explain to me in great detail how generous they would be if they won the lottery. He was actually looking back to the past and saying how he wouldn't mind paying something he isn't going to pay.
I am also not working and so wouldn't pay it but I think I understand why those who would could change their ways dramatically.
My worry on the whole idea is that SS is already not a good plan if you look at it in terms of return on investment. Making it more progressive (hell for $100 in covered income after the last bend point you get less that a 4c increase in benefits) will make it a worse plan for those with more earnings. Investing my contributions in inflation protected securities (essentially) albeit with longevity insurance doesn't seem like a winning strategy. Few here invest like that.
The evidence is clear that savings rates have been depressed by SS so increasing the SS tax rate seems like a bad idea to me.