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A correctly fitting boot is always going to be warm. Like seriously, always. You have an almost-airtight plastic box with a thick, squishy foam bit wrapping your foot which probably has some nice merino socks on it. If your feet feel cold, it's almost certainly because you're losing circulation to them. The fact that you said that your boots are probably way too small, and that you've had the toe box punched way out, tells me that your boots probably don't fit that well. They're not inherently cold, they just fit terribly and it's squashing all your veins.
It's time for new boots, dude.