Honestly, why have government ran mandatory retirement fund? Why not simply let the market and people chose their investment strategy and do what they want wit

Honestly, why have government ran mandatory retirement fund? Why not simply let the market and people chose their investment strategy and do what they want with their 401Ks? "Just give us your money, it's the law, we'll manage it" "Woops we lost it with crypto. Don't worry about us, we cashed our flat rate commission so our bonuses are safe!" Only guaranteed with a mutual fund is that the manager will cash the yearly fees.