I think he meant, can politicians only do what is best for the country, or can only concentrate on getting reelected, not both. I think the two are not mutually exclusive, but they do tend to operate at cross-purposes. Running for a major political office requires raising huge sums of money to run a feasible campaign. The little guy's paltry sums take a lot longer to accumulate than getting some rich contributors to provide major bank-rolling of a campaign. So, pols are beholden to those deep pocket contributors, and that money isn't without strings. So, I think any successful/career politician has to serve the wishes of those fat cats to some extent. The pols can try to dress it up as something else, but in reality "money talks." Now, I would think that once a candidate has made a name for himself, he/she can worry less about serving the wealthy and still run successfully. Hopefully the goal then is for that pol to work on the betterment of the country and leaving a legacy of good works.
My understanding (albeit far from thorough) of the problems with Social Security/Medicare include that the money paid by payroll deductions into the programs has not been kept separate . . that it is mingled with other monies and in fact has been borrowed or raided (whichever term you prefer) for other uses. So, of necessity, current taxes revenues have to be diverted to help pay for those programs. Also, I hear that for any type of pension plan that includes health benefits, the medical costs are significantly more of a burden to those plans than the in-cash payments. Medical cost increases have far out-stripped inflation, which is why managed care has become the standard now. It started with the private insurance companies, but Medicare and Medicaid had to adopt managed care (thus, denying some care that they previously paid without questioning it) in order to have some control over rising costs. When you add a large "Boomer" population of retirees that must be supported by smaller generations of working taxpayers, then the burden is not difficult to imagine. Like I said, in many respects, Social Security and Medicare are ponzi schemes . . . the biggest question is, When does that scheme go bust and which generations of people who paid into the plans will not receive anything close to what they paid or was promised?