Why has Donald Trump not taken any questions since he lost the election?

Answer 1

Why should he?  He knows he won't be a two-term Prez, so he has nothing to discuss.  The better question is:  What has Biden said of any substance since he won?  Does anyone have any idea what he intends to do about the economy or the pandemic, for instance?  Reading Dem scripts about how all the problems were caused by Trump in the prior administration tells us nothing.

Answer 2

Because the only meaningful question is: "why not concede the election?"

Answer 3

Probably because he knows he's lost and would have to admit it.