Peter, possibly the only reason why I would pay the income tax if I was an American citizen, would be to avoid the "law" requiring you to pay it (big men with guns and badges, and the precedent set in jurisprudence (approximately 22 cases)).
As far as the number of people that "think income tax is optional (or illegal)", is most definitely a small group of (informed) individuals, but they're not akin to delusional members of the flat earth society, or those that deny evolution.
Here's a link to Aaron Russo's documentary
, which is probably the best documentary on the unconstitutional and thenceforth illegal income tax. It's broken down into 11 parts, so it's easy to watch at anyone's leisure, and I hope many of you will.
It would be interesting if someone was to call their congressional representative and ask them to provide them with the law that states that you have to pay it. That's the only way somebody can disprove that it's illegal, rather than denigrating people that think otherwise based on research that they've done.
The subject at hand doesn't even affect me, but I seek the truth regardless. Put it this way-if I lived in the United States, and had the questions and beliefs that I am setting forth, I'd seek answers, rather than accepting what's being shoved down my throat. Maybe I'd be proven wrong, but I'd take comfort it knowing.