Because you can’t draw how little you want. The IRA and 401K rules stipulate that you have to meet minimum dispursements based on your age in retirement.
Starting at 70.5 years of age, you must take a minimum distibution based on the balance. If your balance is $1 million, you’ll need to take out $35K whether you need it or not and have it be income. As you get older it goes up faster.
If you are 65, your life expectancy is 85 as a woman. At 80 you have to take out at least $53K if you have a million balance. 85 you need to take out $67K. and on.
The income will be counted as income. If you have Social Security, it will be additive on top of social security.