It's realpolitik. If you think it's worth fight for then why choose a losing battleground?
"I think the people I disagree with should limit themselves to this arena," is a guaranteed way of losing. It's like saying, "I think we should all line up and fight in a big field," when your opponents bring in the guns and artillery you say, "Yes, you overpowered us and won, but you did it in the wrong way so we didn't actually lose."
Again, it seems that free speech is losing in the marketplace of ideas, why wouldn't that make you change your mind? Holding onto a losing idea is exactly how the marketplace of ideas is not supposed to work.
The point of the marketplace metaphor is that good ideas will outcompete bad ideas. That's only possible if people are willing to change their minds.
How do you think the marketplace of ideas works if people don't do that?
Also, it's a perfectly valid option to support a team that you think is going to win. Why would someone put themselves through losing? I think that's the position that requires more justification.
The marketplace metaphor implies there are buyers and sellers. The sellers are the ones fighting to make their case for the ideas they are 'selling.' The 'buyers' are the audience, those as yet undecided. Once a buyer has 'bought' an idea he either becomes a seller or leaves the market.
Generally the sellers aren't the ones changing their mind - you only care enough to 'sell' an idea if you believe in it strongly.
The metaphor involves people entering the market undecided and being convinced of one idea or another. Generally people who've already made up their mind don't enter the market - unless they're motivated enough to become sellers.
That's how the metaphor works.
As to your 2nd - what's the point here? Both of us know why people support the football teams they support. What's the dumb act about?
