And this attitude is precisely why people won't support SCS.

You might think think this, and people like you might think this, but it convinces no one else, and telling them they're selfish is a great way to get them to vote against you in even greater numbers.

Try building some bridges and explaining how SCS sites actually reduce crime, needle waste and such. Then talk about how we need housing on top of that.

Yes, people are selfish and care about their own interests. They're people. You need to work within those constraints if you want change. If your plans for a better society involve expecting better people, you won't get there.