How can I export an Event Income Detail report to CSV/Excel?
Reports that provide a simple table are more amenable to export as CSV.  The Event Income Detail has different sections to it which does not fit well for a CSV format - what column headings would you use?

Whether a report offers a CSV export option depends on the settings in the code.  The Event Income Detail report is provided by CRM/Report/Form/Event/Income.php  You will see a line there saying

$this-&gt;_csvSupported = FALSE;


If you were to change that to TRUE then the export option would be shown, but the rest of the report does not handle producing a CSV so that's not useful! ... unless you use that as the starting point to customise it to produce the output you want.

FWIW, pasting into a spreadsheet works pretty well: run the report, highlight the section of the report that you want, copy then paste into a blank LibreOffice spreadsheet, and you often end up with something usable.  That might work with Excel too.