Because cyclists waste hundreds of dollars each year on cycling-specific accessories when non-cycling-geared materials would suit just fine (or often, much better).
Generally incorrect. With winter gloves I would agree.
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In response to the OP:
I like picking up my winter gloves from outdoor sports stores. However, I spend around $30 a set. I find the typical xmart special lacking.
When I am warming up no matter how thick my gloves are my fingers are cold. Once I am warmed up they are generally toasty.