I have problems with people who abstained. The hard thing is, how do you change voter behavior?
That depends on what you want to accomplish.
If the only thing that matters to you is going to the polls every 1-2 years, than non voters are meaningless.
If you want to transform society. Voting is only one vector. Unions, mutual aid, protest, consciousness raising, and so on don't have anything to do will polls, and non voters can be valuable allies.