Next, your estimate for property taxes is similarly low. I don’t live in CA but where I live taxes are roughly 1% of the assessed value. Let’s say the county assesses your 1m home for 900k - and not to mention the assessment will probably increase over time - so you’re looking at about $750/mo there.
You totally forgot about homeowners insurance - required for that loan plus it’s included in the front end dti ratio. That will set you back another ~$150 per month.
That adds up to a total of $4556, almost 14% higher than your estimate and representing one trip to Disney world’s worth of extra spending over the year.
Often overlooked is the savings you should make for maintenance, repairs, and improvements. Only after buying and selling a few houses do I finally appreciate exactly how expensive they are and how “only” a $100 per month difference adds up - quickly.