Is it actually that bad? SF rents are certainly not low, but if you check Craigslist/PadMapper, it would seem difficult to pay $4k, let alone that being the median.
More anecdotally it is basically impossible to get a studio for less than $2k or a 1BR for less than $2.5k-$3k. I pay ~$1700 but have 1 bedroom in a 4BR apartment. If you are willing to live with roommates rent can start to become "reasonable" (assuming a $100k+ salary), but you're kind of screwed in SF proper if you want to be on your own and pay less than $2k.
Your post suggests you must be single, probably living either with your parents or with roommates. Perhaps 75k works if you are in the above two situations, but not otherwise.
Consider that 75k, after taxes will be 50k.
Assume you are saving zero for IRA/401k, you still have other costs -- healthcare premiums, car/bus/train fees, etc.
Oh, and food. Doctor co-pays, dental co-pays.
Now if you are married with kids:
1. Hospital co-pays, premiums, co-insurance, $45 drug co-pays, everything comes to about $5k/yr if you are just moderately sick.
2. You cant live with roommates, you actually need your own home. Can you imagine raising a family with roommates?
3. You def need a car, possibly two.
Forget about saving up for a house, most will be $1m+
Some people will say -- "oh, you are married, now you have two incomes" -- sure, until you have kids. Then most of your second income goes to child-care, and in the early years, you will pay MORE for childcare than you earn!
More anecdotally it is basically impossible to get a studio for less than $2k or a 1BR for less than $2.5k-$3k. I pay ~$1700 but have 1 bedroom in a 4BR apartment. If you are willing to live with roommates rent can start to become "reasonable" (assuming a $100k+ salary), but you're kind of screwed in SF proper if you want to be on your own and pay less than $2k.