Multiple independent datasets show that startup failures were significantly higher from late 2023 through at least late 2024 than in the 2021 boom period, matching Sacks’s prediction both in timing (roughly the 18 months after October 2023) and in mechanism (2021‑era companies running out of runway and unable to refinance).

Key points:

• 2021 as easy‑money baseline: 2021 was a record year for global VC funding, with around $621–681 billion invested worldwide and more than $300 billion in the U.S., reflecting extremely loose capital and supportive conditions for startups rather than mass shutdowns.(news.crunchbase.com)

• Sharp rise in shutdowns starting 2023: Carta data (U.S. startups) show 467 shutdowns in 2022, rising to 770 in 2023, which Forbes describes as the highest number of shutdowns Carta had ever tracked and calls 2023 “the most fatal year for startups.”(forbes.com) Q3 2023 alone saw 212 shutdowns, the highest quarterly total since Carta began tracking this in 2012, up 50% year‑over‑year.(southernstartups.org) This is already a clear elevation versus the 2021 boom environment.

• Further acceleration into Sacks’s 18‑month window: Carta reports that shutdowns continued to accelerate into 2024, with Q1 2024 reaching 254 closures—a new quarterly record and 58% more than Q1 2023, after a 124% jump between Q1 2022 and Q1 2023.(carta.com) Full‑year data show 966 shutdowns in 2024 vs 769 in 2023, a 25.6% increase and again a new high.(techcrunch.com) Forbes and Carta both note that 2024 saw the highest absolute number of startup shutdowns ever recorded in Carta’s data.(forbes.com) TechCrunch and others expect 2025 to remain “another brutal year of failed startups,” indicating the elevated failure environment persisted into the first part of 2025.(techcrunch.com)

• Direct link to 2020–2021 funding cohorts and inability to raise: Multiple analyses explicitly tie these failures to startups that raised large rounds in 2020–2021 and then hit the 18–24 month mark in a far tighter funding environment. Carta’s head of insights notes that companies that raised in late 2020 and early 2021 were facing their next raise in 2022–23 just as capital dried up, forcing shutdowns.(bizjournals.com) The Financial Times similarly reports a 60% rise in startup failures as many firms that raised during the 2021–22 boom exhausted their cash and couldn’t secure new funding on acceptable terms.(ft.com) A 2025 Carta‑based review emphasizes that the wave of closures in 2024 was “concentrated” among startups funded in 2021–2022, exactly the dynamic Sacks described.(forbes.com)

• Global corroboration: Outside the U.S., Tracxn data on India (the world’s third‑largest startup ecosystem) show 15,921 shutdowns in 2023 and 12,717 in 2024, versus only about 2,300 shutdowns over 2019–2022 combined, a roughly 12‑fold jump, again indicating a post‑2021 correction with elevated failures.(magzter.com)

Across geographies and data providers, the pattern is consistent: 2023–2024 (and into early 2025) show a markedly higher level of startup shutdowns than the 2021 ZIRP boom, and analyses explicitly attribute this to companies that raised big 2020–2021 rounds running out of cash in a much harsher funding environment. That matches Sacks’s prediction on both direction and timing, so it is best classified as right.