Made some calculations several weeks ago. To pay off the delegation leasing (with no selfvoting) you need to make something about 16-20 full-power (100%) votes per day. And this is not possible cause when you make a 100% upvote having 100% VP - you'll have to wait about 2,5 hours to recover your VP. So you can make only 9-10 full-power (100%) votes per day.
This is the reason you have to selfvote...
The system is designed to only have 10 full votes per 24 hours.
If you can't cover the delegation and add some value to the rest of the community too, don't get delegation. I pay for part of mine out of my normal earnings plus, I have a good deal on it as I got is before the SBD spiked. However, if you are paying for delegation and not converting any of the SBD to steem, you will of course run at a loss on nearly every delegation out there.