It starts with Congress. Unless you change the laws governing the entitlement programs, the benefits and rates of increase follow established formulas and indicies. There are political considerations when you are dealing with benefits affecting over 75 million people and the millions more who are currently paying into the system.
Politicians don't JUST DO IT if there is a political price to pay or an advantage gained. I suspect that most voters want to keep the benefits coming and the current rules kept in place. How many Americans would support raising the retirement age to 70? Or raising the OASDI tax?
It takes 15 minutes to pass a law that undoes all of that. There is no such thing as forced entitlements. There is nothing that requires a drug addict to take the next hit, an alcoholic to take the next drink, a smoker to take the next drag.....each one of those, and each spending bill, could be that last in the chain...at any time.
There are political considerations when you are dealing with benefits affecting over 75 million people
So what? So you mean there is no easy, convenient way to quit their habit? Too bad. But don't pretend that it's "impossible." It's entirely possible at any time, the process allows it. What seems "impossible" is to elect congresscritters that have the will to quit.