Donald Trump ultimately did skip every Republican primary debate in the 2023–24 cycle; contemporary coverage and reference summaries note that he “did not attend any primary debates” and that he secured the nomination “despite not participating in any of them.” (en.wikipedia.org)

He clinched a majority of delegates for the 2024 GOP presidential nomination by March 12–13, 2024, and was formally nominated as the Republican presidential candidate at the Republican National Convention in Milwaukee on July 15–18, 2024. (cnbc.com)

Throughout the competitive primary period he maintained a dominant polling lead over rivals, with national averages around 50–60% for Trump versus teens for his nearest competitor and many individual polls showing 40–50+ point advantages well into late 2023 and early 2024. (fivethirtyeight.com)

Taken together, these outcomes match Friedberg’s forecast that Trump would likely skip all GOP primary debates yet still secure the Republican nomination while maintaining a large polling lead.