... Social Security and government pensions. Again, no choice. If we could keep our money and decide where to invest, I think we'd be better off. You'd have more money in retirement if you just bought safe US Treasury bonds all your life. Plus, if we die before retirement, our families would get an inheritance of the value of those savings. Now the government keeps all that money we and our employers gave them our entire lives...
It is a bit more nuanced than that. I see your points, and they are valid ones, in general. But there are some big IFs implied: IF you keep your money and IF you invest it wisely. Getting to a retirement age and finding out you didn't is too late. It is hard for young people to have such willpower and wisdom to set aside 12% of every check and never dip into it in times of crisis. It is also hard to resist the call to invest in stocks in times when everybody and his uncle is making big bucks in the stock market, only to find yourself in 2008 when stocks lost 80% and your time to retire has just come up.
I am generally in agreement with your overall philosophy of personal responsibility and risk-taking. However, it is one thing to punish a young person for foolish financial decisions... there is time for them to learn from their mistakes and recover from it. Not so when you are about retirement age. At that time, and in particular later, there is nothing they could do to recover.
It is easy to say let them rot, it is their fault. But do we really want to see new hordes of homeless old people on the streets? Or should we let them out in the cold, for passing polar bears to find them, when their teeth can not chew seal hide anymore? Not so long ago, maybe 100+ years ago, in the mountainous regions in my country, they would take old people out, put a bread on top of their head and the whole village would stone them to death, as they couldn't pull their own weight anymore.
The level of civilization of a society is measured, among other things, by how they treat their old. Social Security benefits are hardly sufficient even for the most modest living, and hardly going to make anyone rich. They are the absolute floor.
In my particular case, if I did what you suggested, I would have ended up with cash savings worth the next 8-10 years of retirement. My parents and grandparents lived well into their 80s. I hope I have their genes. If so, I would run out of savings somewhere half-way. And then what?