Fellow Northern California homeowner here. You can sell it and you will net a return. I'm not sure I understand your gripe. It sounds like you're annoyed about the hassle of moving , the associated fees, etc. But the parent's point is valid - the appreciation of value of your house is great for you.
> 1. Capital gains tax
Note - if it's your primary residence you get capital gains relief on the first $500k.
> 2. Real estate agent fees
If you're in the bay area, then you negotiate these down to the minimum (IIRC 2.5%) because the market is so liquid and the agents add very little value (if you're smart). Also, you can negotiate not to pay the commission if you're the buyer. So the only burden is on the sale, which is less impactful since you've already made a profit on it.
> 3. Higher property taxes
Yes, this is a bitch in CA...see next point.
> we can't afford to move!
Clarification - you can't afford to move in the general vicinity, but you could certainly move to Nevada (for example). If you are not viewing your house as an investment, then guess what? You get to live in an area that is high demand! Good for you for timing the market appropriately when you bought.