There is a mix of retirements:
Pensions: Social Security, Military, RR, etc.
IRA/401K: Money saved where you draw and principal declines
Investments: Money that pays dividends, but you need to avoid decreasing the principal
Rental Income: Money from properties owned.
Annuities: Money paid every month for a given length of time, but unlikely to account for inflation.
Other: Inheritance, savings, other.
Pensions appear to be the best, until they run out of money and you lose it. Government pensions appear safe, but what the government gives, the government can take away.
Best to have a mix of all for when you don’t get what you expect.