Solas does not consider his actions are evil because he does not believe in the concept of good and evil, just cause and effect. He regrets his action will result in a loss of life partly because it conflicts with his belief that "every free thinking individual has the right to exist". He overcomes this objection by convincing himself that the modern world is broken, its people are broken even if he were to acknowledge them as his own, who for the majority he doesn't. He states "I am not a monster", more because he knows that is how a friendly Inquisitor, for whom he had respect, might perceive him, not because he regards himself as a potential monster for his actions. It bothers him that someone he respected might think badly of him, not enough to stop his plan, but enough to admit "you deserve better". He wants to save his people and it is regrettable that will result in the annihilation of those not his people but he even suggests to a friendly Inquisitor that they would do the same. To him numbers are immaterial, it is the general principle that counts. If you destroy his people in order to stop him, then in his mind you will have proved him right. You are just choosing one set of people (yours) over another set of people (his). Just as if a pack of wolves kill a beer that is threatening them in order to survive or you killed a dragon and its babies in order to maintain the safety of a village.
If he does not respect the Inquisitor you could argue that his responses are more honest and give a clearer insight into his thinking. There is "no benefit" to himself in letting innocents come to harm before it's necessary, so that is why he helped against the Qun. Also "The Qunari offend me". This is because their philosophy denies the free will of the individual. He saves the Inquisitor because chaos and panic would ensure if they died. It fits with his plans that southern Thedas is at peace and complaisant about the danger. He will have observed that the nobility in Ferelden never got off their sorry a***s during the Breach to help the common people, so are unlikely to be motivated to do anything now. The nobility of Orlais are too busy engaged in their own Game. He has effectively undermined the trust in the organisation that could be effective against him and probably guesses that their power will be stripped back as a result. He will likely still have agents if he wishes to keep an eye on things and direct events as he wishes. (I liked to think that he wasn't expecting the Inquisitor to simply disband because people in power generally do not easily relinquish it).
I don't know if the terms we use in the modern world really apply to Solas. If Solas was killing the other races so his people could take over in the current world, that would be racist because that is his principle aim, to replace one group with another. What he is doing is "correcting" the current world by restoring it to its natural state (with no Veil) and thus restoring his people to their natural state. If the current races manage to survive the change, he is not going to kill them and would likely encourage peaceful co-operation between the two. It is just that he doesn't envisage them being able to survive it. In fact calling him racist is too narrow a term. It is not just the humans, qunari and dwarves that will die, but all the other flora and fauna of the world, if it is going to be a mass extinction event. That goes way beyond mere racist.
I'm not defending his actions, just trying to understand the way his minds works.
Actually it begs the question, why does he think that only his people will survive? He talks of fiery chaos but that would surely affect his people too? Is he going to hide them somewhere, the Crossroads perhaps, until it is all over? Were there no humans around at all before he raised the Veil? The timeline suggests there were. The dwarves certainly were. The Neromenians were already in the north when the elves felt the Quickening. Where were they before that?