If you're a 'full-time' domainer and you focus on a small, high quality portfolio, you're going to go out of your mind with boredom. You have to find other things to do, that simple, even if money isn't an issue.
One of the less talked about positives of owning a big portfolio is non-stop action.
Would you rather have 5 mini-buzzes a day or 1 every 3-6 months?
It's a definite consideration for your mental health and feeling purposeful. It's more easily achieved with a good-sized portfolio, even if it is time consuming.
That said, I ain't gonna change.