Here's why:
* Euphemism: A euphemism replaces a harsh or unpleasant term with a milder one. This phrase isn't doing that.
* Innuendo: Innuendo implies something suggestive or scandalous without directly stating it. This phrase doesn't hint at anything inappropriate.
* Rhetorical: Rhetorical devices are used for persuasive effect. While the phrase might be used to persuade, it's not a specific rhetorical device.
* Definition: A definition provides a meaning for a word or phrase. This phrase doesn't define anything.
* Weaseler: A weaseler is a word or phrase that weakens a claim or softens a statement. "At the end of the day" is used to dismiss opposing views and suggests that the speaker's viewpoint is ultimately more important, even if it doesn't necessarily hold more weight logically.
In Conclusion: The phrase acts as a weaseler by softening the assertive nature of the statement and implying that the speaker's view is superior without providing strong justification.