Rent is only $5K in the Bay Area if you want to live in one of the "luxury" complexes or a single-family home. I pay $2600/month for a 2BR townhome that's about middle-of-the-road in quality. Single engineers can do a lot better by living with roommates; if you're willing to double-up in a 2BR or triple-up in a 3BR you can do about $1200/month. (Some of the units in our complex actually have 4 young men living in a 2BR; they pay $650/month in exchange for living like they're in college again.)

The capital-gains portion of your wealth (which can be appreciable; see below) is taxed at 15% Federally and 10% CA.

If you buy a house that's an investment, not an expenditure, so it is not included in monthly expenses. 45% is your marginal tax rate, not effective tax rate.