Have you ever brought in cash when appraisal is too low for loan?

[Jonathan Oh]

I tell people that the lender requirement of having appraisal come in at or above purchase price is a good thing. In a way, it gives some assurances whether you are overpaying or not. I buy turnkeys (my personal choice) so I wouldn't bring in extra cash if appraisal comes in lower. I also never heard of anyone who actually came in with cash to make up the difference on a deal. So just curious, why would investors do this?