Was Trump justified in his reaction to his claims of a stolen election?

This is more about Trump's behavioral reaction to apparently losing the election, rather than the claims he made.

He made these claims previously in both elections, including the one he ultimately won, along with the fact he made those claims quite some time before the voting began and the winner was announced. He stated things in the last election like "We already won the election/state" a few days before the results were announced and everything was being processed.

After he apparently lost, he began to obsess over the fact that he had been swindled by his competitors, despite maintaining such confidence before hand he would win. He filed countless lawsuits which were are unsuccessful and dismissed from both sides because he apparently didn't provide any credible proof or evidence to his claims. Then he encouraged the idea for the capitol protest on Jan 6, 2021, which resulted in a lot of chaos, injuries, and even some fatalities and became an unforgettable and unnerving moment in the history of politics.

With all that said, do you believe Trump was fully justified into acting out this way in front of everyone, or was he following a lost cause that he couldn't change and overreacting a bit too much?