Show your proof that selfishness all by itself qualifies as evil.
Evil is a quality. A quality divided remains the same quality, differing only in degree and not in kind. Even if it were true that the quantity of evil were insufficient to outweigh the balance of good, nevertheless the evil remains. Less selfish would still be selfish, and therefore a blemish on the characters. Theft of a little remains theft. Slightly dishonest remains dishonest. A little bit drunk, is still not sober. A little bit unfair or a little bit unjust, is still unfair and unjust. And incidentally, that's what selfishness inherently is and inherently what it's product is - unfair and unjust.
Or looking at it another way, since evil is a quality of relating to abrogation of worth leading to a false judgment, any misjudgment however small remains evil. Small misjudgments of worth would tend to lead to small evils, and larger misjudgments of worth would lead to larger ones. But again, any non-zero error would remain evil and be a blemish on the judgment.
It is the deceit of evil to say, "Just a little won't hurt." But it is a cancer, it grows and grows. And the Dunning-Krugar effect applies to errors of all sorts. Everyman looks until he finds someone he thinks is worse than he is, and so justifies himself. But that's not the standard.
Or alternately, the general approach I'm taking here is not novel. How much evil existing in a man's heart weighted him down to damnation? According to Egyptian myth - no more than a feathers worth? How great of offense against Dharma is necessary to force a soul to remain in the cycle of rebirth and death - any amount at all. How much sin makes a man unrighteous? Again, any amount at all. Why should you rely on me for instruction? Are there not many greater philosophers, poets, thinkers and prophets than I am? Go and heed some of them, and then I'd be flattered if you returned and asked questions.
Here is my experience. It doesn't matter what I say to you. You aren't going to listen. To listen would require you to accept that your own selfishness - and whatever other failings you may have - was evil. And while people may be quick to claim other peoples faults are wrong, they are little inclined to claim their own.
In my experience, people are quick to claim every little negative as some big, bad EVIL.
No, I'm happy to call a little evil a little evil. But, if I could choose to rid the world of all the little evils, or all the great ones, I think I'd be inclined to get rid of all the little ones. I think that there is probably more evil in the great long tail of evil, than in the more salient events that draw or attention, and that without this mass of mundane evil the great evils of the world would be diminished because an army would exist to resist them at every hand. But because people are at best a little bit selfish...