A monetized viral video can earn thousands of dollars in advertising revenue. It could even be tens of thousands of dollars if the video receives millions of views.
"YouTube shares 55% of its ad revenue with video creators and books an average of $7.60 per 1,000 ad views. That means you get about $4.18 for every 1,000 views of ads shown on your videos."
So you really need a lot to make it worth the extra work