Yeah, anyone I know who says something like "Bernie or bust" or equivalents about their favourite politician, regardless of the country, I will try to explain that even if they cannot get their favourite candidate, it would be better for them to choose the next best candidate even if the next best candidate is much worse than their favourite candidate.
This is something that is true by definition. Your best available option is...your best available option.
Now, if someone sincerely does not want their best available option, or they believe that the best available option is not worth lining up to vote for, well...then that is their choice. I don't agree with their choice, but it is theirs to make.