Normally the losing side concedes in the hope to not sow division. But Trump only does things in his interest so... yet another norm lost.
Nothing is official-official until December 13, so he has the right to pursue whatever remedies he wishes in the meantime, but the lack of trust he is fomenting right now, today, is harmful to America, and that's running counter to long-established norms.
The reason his cases keep getting dismissed is there isn't any evidence of election fraud.