Overall judgment: The prediction is wrong. While the stock market did rally and vaccines ultimately proved highly effective (later in 2020), the core political and epidemiological claims did not occur: Trump did not "go all in" on masks, U.S. daily COVID deaths did not fall below 250 by mid‑September, he was widely judged to have lost the first debate, and he lost re‑election.

Below is a breakdown of each element:

1. “Trump goes all in on masks” in the weeks after July 31, 2020

   • Trump briefly called mask‑wearing "patriotic" (July 20) and at a July 21 briefing urged people to wear masks when they couldn’t distance. (cnbc.com)
   • But he refused to impose a national mask mandate and explicitly opposed one, saying he wanted people to "have a certain freedom" and did not believe in a national requirement. (washingtonpost.com)
   • Through August–September he waffled publicly, saying "the mask, perhaps, helps," but also stressing that "masks have problems" and mocking Biden for frequent mask use; he continued to hold packed rallies where many supporters were unmasked. FactCheck.org concluded in late September 2020 that Trump "has not been clear" in support of masks and that his messaging was inconsistent. (factcheck.org)
     Verdict: This is false; he never adopted a strong, consistent, national pro‑mask stance that matches "goes all in."

2. “Vaccine starts to show promise right as the debates start” (late September 2020)

   • The first major Phase 3 efficacy announcements—the kind of news showing clear promise—came in November, not September: Pfizer/BioNTech reported >90% efficacy on November 9, 2020, and Moderna reported ~94.5% efficacy on November 16, 2020. (pfizer.com)
   • Earlier in 2020 there were Phase 1/2 results described as “promising,” but no major new breakthrough efficacy news landed around the first debate on September 29. The big step‑change headlines came weeks later in November.
     Verdict: The directional idea that vaccines would look promising in 2020 was right, but the timing (“as the debates start”) is wrong.

3. “Deaths plummet… under 250 deaths per day in America by September 15, 2020”

   • On September 15, 2020, U.S. cumulative COVID deaths were about 194,500, up hundreds from the day before. One daily summary (from JHU data) shows +455 U.S. deaths over the prior 24 hours, well above 250. (haitilibre.com)
   • The U.S. passed 200,000 total deaths by September 21, 2020, implying an average daily increase of roughly 700–800 deaths around that period—again far above 250/day. (en.wikipedia.org)
     Verdict: False; daily deaths did not fall below 250 by mid‑September.

4. “The market rips” in this period (Aug–Sept 2020)

   • The S&P 500 closed 3,271.12 on July 31, 2020, rising to 3,401.20 by September 15, 2020, and had already rallied more than 50% off the March lows. (statmuse.com)
   • August 2020 was the S&P 500’s best August since 1986 and saw new all‑time highs; financial press described this as a record‑setting rally that fully erased the pandemic crash losses. (cnbc.com)
     Verdict: This part is basically correct—U.S. equities did rally strongly.

5. “Trump does well in the late‑September debate and ‘sails in’ to re‑election”

   • The first presidential debate took place on September 29, 2020 in Cleveland. (en.wikipedia.org)
   • Post‑debate polls found viewers thought Biden won by a wide margin: a CNN/SSRS poll reported 60% of viewers thought Biden won vs. 28% for Trump; a CBS poll showed Biden 48% vs. Trump 41%. Commentators across outlets called the debate a "disgrace" and "the worst presidential debate" they had seen. (en.wikipedia.org)
   • In the November 3, 2020 election, Joe Biden won 306–232 in the Electoral College and about 51.3% to 46.8% in the popular vote, defeating Trump. (dashpolitics.com)
     Verdict: False; Trump was widely judged to have lost the first debate and he did not win re‑election.

Synthesis
Out of the chain of events Jason predicted:

• Masks: wrong.
• Vaccine timing around the first debate: largely wrong on timing.
• Deaths below 250/day by mid‑Sept: clearly wrong.
• Market rally: right.
• Debate performance + easy re‑election: wrong.

Because the major political and public‑health claims failed and only the market piece really materialized, the overall prediction is best classified as wrong.