I think his ego got the best of him.
I can imagine it must be very flattering to have such powerful and influential people in your ear basically begging you to run. Not to mention the fact that once again, they (GOPe) completely underestimated Trump yet again.
I have said it before...I actually like Desantis but what I found out through this is his inability to read a room.
2028 was - and still could be - his time. If so, he needs to develop better instincts.
He has proved to be no more than a politician, and I use that word as a bad thing. He will do and say whatever it takes to win and does not have the best interests of the USA nor the citizens of the USA at heart.