I didn't contribute for 21 years while raising kids so definitely I'll be a net gain - in current form, I would probably get half of the SS that my dh gets (since I doubt my 12 years before kids plus the years I work from now until say age 70 will be > half his - I had to start at the bottom of the pay scale). As far as Medicare, I think one qualifies with 10 years' credit? so definitely contribute less than I would take out.
FYI, Ryan's plan for SS reduces "home-maker" benefits to 1/2 of the average SS benefit - much less than my dh's. I am for this and for tying SS to life expectancy and raising Medicare age to 70 in order to save the programs.
Of course, all that is moot if we decide to retire in Jamaica (where medical and COL is very cheap) - in which case, we'll have put in much more than we receive (0) - who knows what will happen? Maybe I'll have grandchildren and my kids need help with them.