He's not showing any signs of giving up
Trump has a number of reasons to not concede yet.
1. Hoping a miracle might still happen. There are still recounts and lawsuits going. Even though there is basically no chance at this point.
2. It appears Trump has been planning for this situation for at least two years. He wasn’t sure if he would get a close race with the red mirage and the blue shift, but it happened. Now he wants to see his plans fully played out.
3. Giuliani and similar people are probably whispering in his ear that he won the election and that things are about to change so that they can continue to get paid and because it is what Trump wants to hear and they want to be on his good side to be part of his future endeavors.
4. The longer it draws out the more he can continue to hold his beloved rallies and get donates for his legal defense and recount fund, which he will use actually to pay his campaign debt.
5. He needs time before Biden has access to working with the administration so that he can do his revenge firings and make sure lackeys are in place to hide the skeletons in secure closets so that the Biden administration won’t get any information that might be determinantal to him.
6. He wants to keep the attention on himself and not let Biden steal his thunder.
7. He needs time to figure out how he is going to get out of this with his ego and fan base intact.
8. He wants to get his post-presidency plans in place so that he can time his very important announcements for a TV network or 2024 run or whatever he is going to do. That includes how he will handle post-presidency debt and possible criminal investigations.
9. He wants build his fan base and create fodder for his TV network. He wants to show that he is not a quitter. That he was wronged by fraud and conspiracy. That will be the big jumping off point for his TV shows and possibly a 2024 campaign.
10. By pushing this to absurd limits he can see who stands with him. This is a loyalty test.
At this point for Trump there is essentially no upside to conceding and many upsides to not conceding. It is bad for the country, but he only cares about Trump.