Marketing data ends up in a warehouse, and the column names chosen during the first import are the ones analysts live with for years.
Human labels make poor column names
Total Clicks (Paid) needs quoting in every query it appears in, and the quoting rules differ between engines. totalclickspaid does not.
Case sensitivity varies by engine
Some SQL engines fold unquoted identifiers to lowercase, others to uppercase, and some preserve case only when quoted. A column created as TotalClicks may be addressable as totalclicks in one engine and not another. Lowercase snake_case sidesteps the entire question.
Consistency beats elegance
Whether it is clickspaid or paidclicks matters far less than every table using the same pattern. Convert the whole field list in one pass so the convention is established before the first table is created, not negotiated per import.
Try it: Convert to snake_case on SeoWolf's Notepad.