Let me describe a hypothetical scenario, I wish to know if my reasoning is correct.
I use source code X, licensed by author Y under the BSD-3 license, in my source code. I intend to adhere to their BSD-3 license.
Then I sell my product under my custom closed source license. My product does not include any source code. My product's license does not contain any part of Y's license. My product has a warranty and that is stated in my license. Y's copyright notice, the list of conditions, and the disclaimer (i.e. the entire text of their BSD-3 license), is included in the every copy of documentation of my product, as per the second condition of BSD-3.
Are those two statements valid while at the same time not violating Y's license:
My product is licensed under my license only.
The disclaimer (written in UPPERCASE) of BSD-3 license is only relevant so that it absolves author Y of any liability, and doesn't have any effect on my license.