Is there anything fundamentally wrong with choosing not to vote?

Not in a democracy

Not really. It expresses an opinion too - that you don't want anyone on the ballot paper. And if enough people do the same thing, that sends a message too.

Yes. You are skipping out on your civil responsibilities. There's only 3 main responsibilities you have by living in a free country: pay taxes, follow the law, vote.

By not voting,you’re allowing the election to sway without you exhibiting your right to vote. Consider if many people felt it unimportant in an entire area. It could have great emphasis on the outcome.

no. but if you dislike the outcome later on, i suggest keeping opinion to yourself

Not really.

It's pretty lazy.

Yes, you’re automatically giving elections to republicans if you don’t vote. https://youtu.be/8GBAsFwPglw

In Australia you get fined for not voting, so the only problem I see with it is to my wallet.

No. That's the thing about democracy. You don't have to vote if you don't want to. If you have to or force to then your just living in a totalitarianism pretending to be a democracy.