I'm not against Han's line. I think it's not believable when he says it, mainly because of the way he says it. I think he should interrupt 3PO a little, not letting him finish his "possibility" line.

If he knows the odds, and he doesn't care, plus he has to be concentrated not to crash an asteroid, plus 3PO always annoys him, I think he would interrupt 3PO, he clearly doesn't wanna hear all that jibber jabber... like "I know what you are going to say, I also know about the odds, but I don't wanna hear you... shut up"

Other thing could be have Han let 3PO end his line and then reply very quietly in an ironical mode "Listen... never tell me the odds". In that case you could say he's kinda making fun of 3PO, and being rather fond of himself. But we don't have that material, ofc (and I mention this hypotethical case not because it's what I wanted for the movie, but just to make my point clear).

The way it is now, it's neither one case nor the other. Han patiently waits 3PO to end his line, to reply impatiently, and violently (?).