I think the Note 8 has been selling okay in the US — of course, not taking on new market share has been a problem. But, Apple and Samsung are, in order, the most profitable mobile phone lines (with most of the profits accruing to Apple).
Samsung claimed that the Note 8 has sold better than the Note 7 (the previous best prior to it being discovered that the thing was an uncontrolled pocket space heater)... but they refused to release any actual US sales numbers. That’s a bit suspicious.
As ZDNet noted: “Samsung did not provide any figures on Note 8 sales, so maybe it only sold one more than the last Note. The Note base is more limited than the broader mass audience who purchase the iPhone or Galaxy S series, but it’s also usually the enterprise crowd or those looking to do everything with their smartphone.”
http://www.zdnet.com/article/samsung-sells-more-note-8-devices-in-the-us-than-any-previous-note/