Yes social security in the U.S is a specific tax that only goes to social security.
Well, it seems that the US has one of the best systems for retirement in the world then.
It’s silly to blame older generations that had it better for the decline.
The total net worth of all billionaires in the US is actually a bit less than the total value of all 401ks alone, ignoring other forms of retirement and savings funds. When things are done "for the shareholders", what makes you think that it's only the billionaires? Retirement by definition benefits from the next generations being held down by low wages to benefit the corporations you're invested in. Boomers, or at least the selfish ones, have a tendency to vote republican because their interests align with billionaires' interests.
But both the net worth of billionaires and total value of 401ks pale in comparison to the total net worth of baby boomers in total.

In comparison, all billionaires put together are under 10 trillion, though they might be slightly over that number now since the last year or two have been WILD for economic growth. But then the boomer number is also ~85 trillion as of April this year and probably over 90 now since the S&P 500 has gone up plenty.
In a few decades it'll be Gen X and then millennials. As a millennial I hope my generation doesn't take the same hard right turn once we're in charge of the economy, but that's like 30-40 years from now and who knows how jaded millennials will have become by then. Luckily we won't get as many decades in charge as the boomers have had.
Don't get me wrong, we should still delete all billionaires, but I'm just saying that this doesn't fix the whole issue of retirement being old people living off young people's work. It'll actually do fairly little because the scale is actually so much bigger.
Wealth Distribution By Age
Across all asset categories, older Americans overwhelmingly hold the greatest share of wealth:
Total wealth: $167.26 trillion
Under age 40: $11.18 trillion, 6.7% of total wealth
Age 40-54: $33.40 trillion, 20.0% of total wealth
Age 55-69: $69.60 trillion, 41.6% of total wealth
Age 70+: $53.08 Trillion, 31.7% of total wealth
Wealth Distribution By Generation
When broken down by generation, Baby Boomers by far hold the largest share:
Total wealth: $167.26 Trillion
Millennials and Gen Z (born 1981 or later): $17.97 trillion, 10.7% of total wealth
Generation X (born 1965-1980): $43.70 trillion, 26.1% of total wealth
Baby Boomers (born 1946-1964): $85.41 trillion, 51.1% of total wealth
Silent and Earlier (born before 1946): $20.18 trillion, 12.1% of total wealth